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151.
The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step. 相似文献
152.
葡聚糖为载体的双亲型LDL吸附剂吸附动力学研究 总被引:3,自引:0,他引:3
合成了以葡聚为载体,同时具有亲水性磺酸基和疏水性胆固醇两类配基的新型低密度脂蛋白(LDL)吸附剂。通过对LDL纯溶液中吸附等温线的测试,比较了以Dextran G-75为载体的双亲型LDL吸附剂与单一亲水型磺酸基配基,单一疏水型胆固醇基吸附剂吸附量和亲和吸附系数的关系。对双亲型LDL吸附剂的吸附动力学进行了初步研究,在LDL溶液中,亲水型磺酸基,疏水型胆固醇配基,双亲型LDL吸附剂对LDL的吸附曲线基本上符合Langmuir吸附方程,另外通过高离子强度NaCl洗脱实验,测定了双亲型LDL吸附剂上具有的磺酸基与胆固醇两类基在对低密脂蛋白吸附过程中所起的配合效果,为下一步作用力机制研究提供了参考依据。 相似文献
153.
The dihydride cluster H_2O_(s_3)(CO)_(10) reacts with ethyne to give a cis-adduct [O_(s_3)H(μ,η~2-CH=CH_2)(CO)_(10)]. The high deuterated cluster D_2O_(s_3)(CO)_(10), the reaction of D_2O_(s_3)(CO)_(10)with ethyne C_2H_2 to form the vinyl product cluster [O_(s_3)D(μ, η~2-CH=CHD)(CO)_(10)], and thereaction of H_2O_(s_3)(CO)_(10) with the deuterated ethyne C_2D_2 to form [O_(s_3)H(μ,η~2-CD=CDH)(CO)_(10)] have been reported primarily in this paper. The two cis-adducts undergo cis-trans-isomerization of μ,η~2-vinyl ligands under a small amount of the nucleophile pyridine. Usingthe combination of deuteration and dynamic ~1H,~2H NMR spectra, we report the experimen-tal evidence determined by the dynamic ~1H, ~2H NMR spectra, mechanism, and kinetic dataof the isomerization. 相似文献
154.
羧甲基壳聚糖/聚乙烯醇/甘油环氧树脂蛇笼型复合螯合膜的制备及对金属离子的吸附性能 总被引:4,自引:0,他引:4
以交联甘油环氧树脂交联的聚乙烯醇(PVA)为笼树脂,羧甲基壳聚糖(CCTS)为蛇树脂制备了具有蛇笼结构的复合螯合膜,研究了其对Cu^2 、Ni^2 、Pb^2 、Fe^3 、Zn^2 ,Hg”^2 、Cd^2 等金属离子的吸附性能,研究表明,该树脂对Cu^2 、Ni^2 、Pb^2 有较好的吸附性能,其中PVA是对Cu^2 的吸附的主要贡献者,而CCTS则是在对Ni^2 的吸附中起主要作用。该树脂可以用于含Cu^2 废水的处理。 相似文献
155.
FuShengWANG BingKuiSONG XiaoLiHAN BaoGuiZHANG 《中国化学快报》2004,15(12):1487-1490
Black lead, Ti-Ru and Ti-PbO2 were used as anode and stainless steel was used as cathode The electrolytic process of producing hypophosphorous acid with four-compartment electrodialytic cell was studied. The comparison of some factors, such as anodic voltage, product concentration and current efficiency, of black lead, Ti-Ru, and Ti-PbO2 electrodes was conducted. As a result, theTi-PbO2 electrode is the optimal anode material used, it can be in electrolytic process for producing hypophosphorous acid. 相似文献
156.
The computational results for curcumin at the B3LYP/6-31G(d,p) level show that the enol form of curcumin is more stable than the diketo form because of an intramolecular hydrogen bond, which extends the conjugation effect in the enol chain, formed in the enol structure. Cis-diketone form can not be obtained, presumably due to the strong repulsion between the carbonyl dipoles aligned in parallel. According to the phenolic O-H bond dissociation enthalpy, curcumin in its most stable form can be suggested to be a relatively good antioxidant. In order to avoid overcoming H-bond interaction and to improve the antioxidant activity of curcumin, a catechol moiety was incorporated into curcumin for designing a novel antioxidant. It is found that the designed molecule is much more efficient to scavenge radical than curcumin, comparable to vitamin E. Moreover, the ionization potential of the designed molecule is similar to that of curcumin, indicating that the designed molecule can not display the prooxidant effect. 相似文献
157.
Feng Ke-Sheng Chen Ru-YuInstitute of Elemento-Organii Chemistry Nankai University Tianjin Wang Hong-Gen Wang Ru-JiCentral laboratory Nankai University Tianjin 《结构化学》1993,(5)
<正> Crystal of the title compound Mr=304. 80 belongs to the triclinic, space group P1, with a = 7. 282)2), b=9. 064(2), c=11. 737(5) A , α=75. 79 (3), β=78. 70(3), γ=88. 49(2)°, V-736. 21 A3, Z=2, Dx = l. 375 g/cm3. The final refinement is converged with R=0. 062 and Rw= 0. 069.The five-membered heterocycle is in envelope conformation. The P - N bond length (1. 68(1)) indicates that the dπ-Pπ bond between P and N of the title compound is stronger than that of the corresponding 4-phenyl compound. 相似文献
158.
铂(Ⅳ)—钼酸盐—丁基罗丹明B缔合显色反应的研究 总被引:7,自引:0,他引:7
本文研究在聚乙烯醇(PVA)存在下,铂与钼酸铵和丁基罗丹明B(BRB)形成离子缔合物,该缔合物的最大吸收位于570nm,摩尔吸光系数ε值为9.26×10~5L·mol~(-1)·cm~(-1),服从比耳定律范围0~3.0μg Pt/25ml,缔合物至少稳定3周。测定铂的条件为C_(HClO_4)=1.4mol/L,C_(MoO_4~(2-)=1.1×10~(-3)mol/L,C_(BRB)=3.8×10~(-5)mol/L,0.08%PVA。考察了40多种共存离子的影响,除形成杂多酸的元素外,大多数不干扰。本法已用于催化剂和某些铂矿中铂的测定,结果较满意。 相似文献
159.
CAI Shu-Hui LI Jun LIU Chun-WanFujian Institute of Research on the Structure of Matter Chinese Academy of Sciences State Key Laboratory of Structural Chemistry Fuzhou Fujian China 《中国化学》1994,12(5):385-391
The band structures of several analogous superconducting A-15 type solid compounds, Nb3X (X=Si, Ge, Sn, Pb), have been calculated by use of the tight-binding method within the Extended Huckel approximation (EHT). By analysis of their energy bands, densities of states and crystal orbital overlap populations, the dependence of the superconducting transition temperatures (Tc) on the electronic structures and bondings is qualitatively elucidated. 相似文献
160.
本文提出了一种快速、简便、灵敏检测痕量多胺的新方法。用对酞内酰胺苯甲酰氯同多胺进行柱前衍生反应,以反相高效液相色谱定量测定多胺含量。在4~500 pmol范围内有良好的定量线性关系,腐胺、精脒和精胺的检测限均为0.1 pmol。 相似文献