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891.
Tadayuki Takahashi Tatsuya Ito Seong-Yun Kim 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):1067-1073
To separate heat-generating Cs from high-level liquid waste (HLLW), the extraction of Cs(I) using 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (calix[4]arene-R14) in combination with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) ionic liquids ([C n mim][NTf2], where n?=?2, 4, and 6) was investigated. Under moderately acidic conditions, the calix[4]arene-R14/[C n mim][NTf2] system showed a higher extraction efficiency (ECs) than that exhibited by the conventional calix[4]arene-R14/dichloromethane system. All extraction processes reached equilibrium within 5 min. Slope analysis revealed that the Cs:calix[4]arene-R14 inclusion complex has a 1:1 stoichiometry. The extraction was found to be exothermic and influenced by the presence of Na(I). These extraction systems exhibited high efficiency and selectivity for Cs(I) in simulated HLLW. 相似文献
892.
Kaito Kuroki Dr. Tatsuyoshi Ito Dr. Jun Takaya 《Angewandte Chemie (International ed. in English)》2023,62(48):e202312980
Formation of borabicyclo[3.2.0]heptadiene derivatives was achieved via boron-insertion into aromatic C−C bonds in the photo-promoted skeletal rearrangement reaction of triarylboranes bearing an ortho-phosphino substituent (ambiphilic phosphine-boranes). The borabicyclo[3.2.0]heptadiene derivatives were fully characterized by NMR and X-ray analyses. The dearomatized products were demonstrated to undergo the reverse reaction in the dark at room temperature, realizing photochemical and thermal interconversion between triarylboranes and boron-doped bicyclic systems. Experimental and theoretical studies revealed that sequential two electrocyclic reactions involving E/Z-isomerization of an alkene moiety proceed via a highly strained trans-borepin intermediate. 相似文献
893.
K Hirabayashi S Iwata H Matsumoto T Mori S Shibata M Baba M Ito S Shigeta H Nakashima N Yamamoto 《Chemical & pharmaceutical bulletin》1991,39(1):112-115
Chemically modified compounds of glycyrrhizin have been synthesized and evaluated for their inhibitory effect on the replication of human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1). Among them, the 11-deoxo compound having a heteroannular diene structure at the C and D rings proved as active against HIV-1 as glycyrrhizin in MT-4 and MOLT-4 cells. It completely inhibited HIV-1-induced cytopathogenicity in both cell lines at a concentration of 0.16 mM. The compound was also effective against HSV-1 with a 50% inhibitory concentration of 0.5 mM [corrected]. 相似文献
894.
M Hori R Iemura H Hara T Sukamoto K Ito H Ohtaka 《Chemical & pharmaceutical bulletin》1991,39(2):367-371
A series of 4-alkoxy-2-(1-piperazinyl)quinazoline derivatives was synthesized and evaluated for its ability to reverse a scopolamine-induced learned impairment in a one-trial passive avoidance task (antiamnestic activity). 2-(4-Allyl-1-piperazinyl)-4-pentyloxyquinazoline (4) showed more potent antiamnestic activity than such reference compounds as aniracetam, idebenone and bifemelane at a wide dose range (1-30 mg/kg]. Compound 4 also exhibited potent anticonvulsive and antihypoxic activities, and was selected as the most promising nootropic candidate agent. 相似文献
895.
I. Katakuse H. Ito T. Ichihara 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,20(1):101-104
The dissociation patterns of doubly charged noble metal clusters (M) n ++ to two singly charged clusters, (M) m Emphasis>1/+ and (M) m Emphasis>2/+ have been investigated using a double focusing mass spectrometer. They are compared with the dissociation patterns from singly charged clusters. The dissociation probabilities to (M) 3 + and (M) 9 + were large and the odd-even alternations were observed in both patterns. 相似文献
896.
O. Ito 《Research on Chemical Intermediates》1997,23(5):389-402
Efficiencies and rates of electron transfer from various electron donors to excited fullerenes (C60 and C70) have been determined by observing the transient absorption bands in the near-IR region, where the anion radicals of fullerenes
appear. From the rise of the absorption bands of C60
−+ and C70
−+ in the near-IR region, electron transfer takes place via the triplet states (TC60
* and TC70
*) under appropriately low concentrations of electron donors. By analysis of the rise curves C60
−+ and C70
−+, contribution of the excited singlet states (SC60
* and SC70
*) in addition to the route of the triplet states (TC60
* and TC70
*) is confirmed. The quantum yield for electron transfer via the triplet states Φct
T was evaluated by the ratio of [C60
−+]/[TC60
*] (or [C70
−+/[TC70
*]). The Φct
T depends upon the donor-ability, donor concentration, and solvent polarity. The back electron-transfer process, which was
evaluated by observing C60
−+, also depends upon the solvent polarity. 相似文献
897.
Yuya Tanikawa Shingo Kanemura Dai Ito Yuxi Lin Motonori Matsusaki Kimiko Kuroki Hiroshi Yamaguchi Katsumi Maenaka Young-Ho Lee Kenji Inaba Masaki Okumura 《Molecules (Basel, Switzerland)》2021,26(10)
ERp57, a member of the protein disulfide isomerase family, is a ubiquitous disulfide catalyst that functions in the oxidative folding of various clients in the mammalian endoplasmic reticulum (ER). In concert with ER lectin-like chaperones calnexin and calreticulin (CNX/CRT), ERp57 functions in virtually all folding stages from co-translation to post-translation, and thus plays a critical role in maintaining protein homeostasis, with direct implication for pathology. Here, we present mechanisms by which Ca2+ regulates the formation of the ERp57-calnexin complex. Biochemical and isothermal titration calorimetry analyses revealed that ERp57 strongly interacts with CNX via a non-covalent bond in the absence of Ca2+. The ERp57-CNX complex not only promoted the oxidative folding of human leukocyte antigen heavy chains, but also inhibited client aggregation. These results suggest that this complex performs both enzymatic and chaperoning functions under abnormal physiological conditions, such as Ca2+ depletion, to effectively guide proper oxidative protein folding. The findings shed light on the molecular mechanisms underpinning crosstalk between the chaperone network and Ca2+. 相似文献
898.
Hayato Toda Shuhei Otake Akari Ito Prof. Dr. Makoto Miyasaka Prof. Dr. Michiya Fujiki Prof. Dr. Yoshitane Imai 《Chemphyschem》2021,22(20):2058-2062
This paper reports the first magnetic circularly polarized luminescence (MCPL) characteristics of racemic helicenes, including four unsubstituted [n]helicenes (n=3,4,5,7) and two [4]helicene derivatives bearing methoxy substituents, in tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO) solutions. The value of |gMCPL| was calculated to be of the order of 10−3 T−1 within 350–430 nm under the north-up (N-up) and south-up (S-up) Faraday geometries in an external magnetic field of 1.6 T. The [n]-dependent MCPL signs were altered by the N-up and S-up geometries. 相似文献
899.
Chihiro Tanaka Takuro Kobori Mayuka Tameishi Yoko Urashima Takuya Ito Tokio Obata 《Molecules (Basel, Switzerland)》2021,26(18)
Cancer cells employ programmed cell death ligand-1 (PD-L1), an immune checkpoint protein that binds to programmed cell death-1 (PD-1) and is highly expressed in various cancers, including cervical carcinoma, to abolish T-cell-mediated immunosurveillance. Despite a key role of PD-L1 in various cancer cell types, the regulatory mechanism for PD-L1 expression is largely unknown. Understanding this mechanism could provide a novel strategy for cervical cancer therapy. Here, we investigated the influence of ezrin/radixin/moesin (ERM) family scaffold proteins, crosslinking the actin cytoskeleton and certain plasma membrane proteins, on the expression of PD-L1 in HeLa cells. Our results showed that all proteins were expressed at mRNA and protein levels and that all ERM proteins were highly colocalized with PD-L1 in the plasma membrane. Interestingly, immunoprecipitation assay results demonstrated that PD-L1 interacted with ERM as well as actin cytoskeleton proteins. Furthermore, gene silencing of ezrin, but not radixin and moesin, remarkably decreased the protein expression of PD-L1 without affecting its mRNA expression. In conclusion, ezrin may function as a scaffold protein for PD-L1; regulate PD-L1 protein expression, possibly via post-translational modification in HeLa cells; and serve as a potential therapeutic target for cervical cancer, improving the current immune checkpoint blockade therapy. 相似文献
900.
The fluorescence excitation spectrum, the MPI spectrum, and the absorption spectrum of acetylene due to the à 1Au←
transition were observed in a gas and in a supersonic jet. A sudden decrease in the fluorescence quantum yield Φf was found above the V4 K2 (46339 cm−1) vibronic sublevel. The decrease is due to predissociation into C2H + H. AK and J dependence on Φf was also found. 相似文献