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121.
Peng-Fei Yao Jun-Rong Meng Lian-Sheng Cui Yong-Le Gan Hai-Ye Li 《Journal of Coordination Chemistry》2018,71(8):1147-1156
Using the N-heterocyclic building block 5,5′-di(pyridin-3-yl)-3,3′-bi(1,2,4-triazole) (3,3′-H2dbpt), four 3-D coordination polymers with diverse connectivity, [M(3,3′-dbpt)]n, M=Co (1), M=Ni (2), M=Zn (3), and [Cd2(3,3′-dbpt)Cl2]n (4), were constructed. By changing the central metal ions, 3,3′-H2dbpt had three different coordination modes. Consequently, 1–3, which are isostructural, have a 3-D 4-connected topology with (42.84) Schläfli symbol. 4 has a 3-D (4, 6)-topology, with (43.63)2(46.66.83) Schläfli symbol. Both 1 and 2 reveal weak antiferromagnetic behavior. In addition, 3 and 4 exhibit purple and blue emission bands, respectively. These results indicate that 3,3′-H2dbpt is an excellent multi-connection linker to construct MOFs with interesting structures and properties. 相似文献
122.
以金属钴盐、2-羟基-1,3,5-苯基三羧酸(OH-H_3BTC)为原料,在碱性条件下,通过水热方法合成了一个钴配位聚合物[Co_2(O-BTC)(H_2O)_5]_n(1),并利用X射线粉末和单晶衍射、红外光谱、元素分析以及热重等方法对该化合物进行了表征。化合物1含有线性四核单元[Co_4O_7],四核单元内的金属离子是通过羧酸氧原子和羟基氧原子桥联的。该四核单元进一步通过O-BTC~(4-)配体在ab平面上形成一个二维层状结构,相邻的层与层通过氢键作用形成一个三维超分子结构。热重分析结果显示化合物1在100℃开始失重。磁性研究表明,化合物1中相邻的钴离子之间存在反铁磁性相互作用。 相似文献
123.
β-Hydroxy-a-amino acids are an important class of amino acids due to their inherent biological investigations[1] and as structural components of more complex biomolecules.[2] β-Hydroxy-a-amino acids have been used as intermediates in the asymmetric synthesis of other compounds.[3] An efficient and convenient concise method for the preparation of optically pure enantiomers of β-hydroxy-α-amino acids would be of general interest. 相似文献
124.
125.
A series of bromo-, nitro-, and bromonitrofluorenones were synthesized chemo- and regioselectively in 90–98% yield via electrophilic aromatic bromination and nitration under mild conditions using water as the sole solvent. These synthetic methods involve simple workup procedures and use only minimal amounts of organic solvents during the purification of products. The newly developed methods have the advantages of being cost-effective and environmentally friendly and could potentially be used for the large-scale synthesis of fluorenone derivatives. 相似文献
126.
Nonlinear Dynamics - Based on the long wave limit method and complex conjugate condition technique, we investigate hybrid localized wave solutions with different forms for the generalized... 相似文献
127.
A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6(1) {(oCH3OC6H4NH3)+(18-crown-6) ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry(DSC) measurements show a pair of sharp peaks at 225 K(heating) and 210 K(cooling),indicating the phase transition is first-order.Dielectric anomalies observed at 225 K(heating)and 210 K(cooling) further confirm the phase transition.The crystal structures determined at 298 K and123 K are both triclinic in P 1.The most distinct difference between room-temperature and lowtemperature structures is the order–disorder transition of the host 18-crown-6 molecule,which is the driving force of the phase transition. 相似文献
128.
129.
电子束与靶物质相互作用时的入射角测量是强流电子束热-力学效应研究中的难点问题. 提出了一种新的基于覆盖不同厚度衰减片微型法拉第筒阵列的电子束入射角测量方法, 与现有方法相比, 可获得具有时域特性和位置分布的强流电子束入射角分布. 以此方法进行了入射角二维分布(r, θ)测量实验, 结果表明, 电子束入射角二维分布与束流箍缩情况紧密相关. 如果箍缩不明显, 则电子主要在自身做回旋运动的同时沿着电力线运动, 多以垂直或者小角度(40°以下)轰击到阳极靶面; 如果箍缩明显, 受E×B漂移影响, 电子束入射角度会明显变大, 从40°以下增至60°左右. 相似文献
130.
Wang PF Duan Y Wang TW Li YZ Zheng LM 《Dalton transactions (Cambridge, England : 2003)》2010,39(44):10631-10636
Compounds [M(2)(4-pi)(H(2)O)(4)]·1.5H(2)O [M(II) = Mn(1), Co(2), Ni(3)] and a heterometallic analogue [Co(1.14)Ni(0.86)(4-pi)(H(2)O)(4)]·1.5H(2)O (4) have been synthesized utilizing a rigid 4-phosphonoisophthalic acid (4-piH(4)). Compounds 1-4 are isostructural, confirmed by their powder XRD measurements. Single crystal structural determinations of 1 and 2 reveal that these compounds display a novel pillared layered open framework structure with zeolite gismondine (GIS) topology. Within the layer, edge-sharing {MO(6)} octahedra are found, which are connected by carboxylate and phosphonate groups along the c- and b-axis, respectively. Dominant antiferromagnetic interactions are propagated between the magnetic centers in 1, 2 and 4. While in 3, ferromagnetic exchange couplings are observed. 相似文献