全文获取类型
收费全文 | 2830篇 |
免费 | 297篇 |
国内免费 | 9篇 |
出版年
2022年 | 14篇 |
2021年 | 42篇 |
2020年 | 30篇 |
2019年 | 58篇 |
2018年 | 52篇 |
2017年 | 67篇 |
2016年 | 68篇 |
2015年 | 117篇 |
2014年 | 120篇 |
2013年 | 154篇 |
2012年 | 163篇 |
2011年 | 191篇 |
2010年 | 137篇 |
2009年 | 117篇 |
2008年 | 137篇 |
2007年 | 145篇 |
2006年 | 139篇 |
2005年 | 149篇 |
2004年 | 132篇 |
2003年 | 107篇 |
2002年 | 118篇 |
2001年 | 74篇 |
2000年 | 74篇 |
1999年 | 65篇 |
1998年 | 34篇 |
1997年 | 26篇 |
1996年 | 25篇 |
1995年 | 27篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 52篇 |
1991年 | 38篇 |
1990年 | 32篇 |
1989年 | 43篇 |
1988年 | 33篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 35篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 20篇 |
1976年 | 10篇 |
1975年 | 10篇 |
1974年 | 15篇 |
1973年 | 17篇 |
1972年 | 11篇 |
排序方式: 共有3136条查询结果,搜索用时 15 毫秒
1.
2.
Somatic embryogenesis and plantlet formation were obtained from 60–75 day old cell cultures of carnation. Callus was generated on MS basal medium supplemented with 2,4-dichchlorophenoxy acetic acid (2,4-D). Removal of 2,4-D during subsequent subculturing of cell suspensions resulted in formation of embroids. These somatic embryos originated from single cells and their early development proceeded normally with clearly defined apical and root meristems. Some embryos developed into plants and were acclimatized to ex vitro conditions. 相似文献
3.
4.
5.
Jeffrey P Mower Pascal Touzet Julie S Gummow Lynda F Delph Jeffrey D Palmer 《BMC evolutionary biology》2007,7(1):135
Background
It has long been known that rates of synonymous substitutions are unusually low in mitochondrial genes of flowering and other land plants. Although two dramatic exceptions to this pattern have recently been reported, it is unclear how often major increases in substitution rates occur during plant mitochondrial evolution and what the overall magnitude of substitution rate variation is across plants. 相似文献6.
Jean L. Santos Paulo R. Yamasaki Chung Man Chin Célio H. Takashi Fernando R. Pavan Clarice Q.F. Leite 《Bioorganic & medicinal chemistry》2009,17(11):3795-3799
New phthalimide derivatives were easily prepared through condensation of phthalic anhydride and selected amines with variable yields (70–90%). All compounds (3a–l) were evaluated against Mycobacterium tuberculosis H37Rv using Alamar Blue susceptibility. The compounds 3c, 3i, and 3l have the minimum inhibitory concentrations (MICs) of 3.9, 7.8, and 5.0 μg/mL, respectively, and could be considered new lead compounds in the treatment of tuberculosis and multi-drug resistant tuberculosis. 相似文献
7.
Summary Several potentially important process variables involved in xylanase production byPenicillium janthinellum in large lab-scale fermentors were efficiently screened by employing a Plackett-Burman statistical design. Results illustrate the design's general applicability to experimentation with fermentation processes. 相似文献
8.
Structural basis of human erythrocyte glucose transporter function in reconstituted system. Hydrogen exchange 总被引:3,自引:0,他引:3
Hydrogen exchange kinetic behavior of human erythrocyte glucose transporter protein in vesicles was studied in the absence and in the presence of D-glucose or a well known inhibitor, cytochalasin B. This is to detect a proposed channel of water penetrating into the protein through which the sugar molecule passes and to monitor any conformational changes induced by the substrate or inhibitor. Analyses of the kinetic data revealed several classes of hydrogens which exchange with readily distinguishable rates. Of 660 hydrogens detected per transporter, approximately 30% exchanged with rates generally characterized as those of free amide hydrogens indicating they are interfaced to solvent water. Since the transporter is known to be embedded deep in the hydrophobic area of the membrane with minimum exposure to the outside of the membrane lipid bilayer, a significant portion of these free amide hydrogens must be at the purported channel rather than outside of the membrane. D-Glucose and cytochalasin B affected the exchange kinetics of these presumably channel-associated free amide hydrogens rather differently. D-Glucose reduced the apparent rate constants, but not the total number. Cytochalasin B on the other hand reduced the total number to one-half without significantly changing the apparent rate constants. The remaining 70% of the labeled hydrogens exchanged with much slower rates which vary 10-10,000-fold, indicating that they are internally structured peptide amide and side chain hydrogens. Both D-glucose and cytochalasin B further reduced the rates of these hydrogens, indicating a global stabilization of the protein structure. 相似文献
9.
10.