全文获取类型
收费全文 | 8683篇 |
免费 | 398篇 |
国内免费 | 1篇 |
出版年
2023年 | 49篇 |
2022年 | 43篇 |
2021年 | 96篇 |
2020年 | 118篇 |
2019年 | 149篇 |
2018年 | 321篇 |
2017年 | 282篇 |
2016年 | 358篇 |
2015年 | 283篇 |
2014年 | 400篇 |
2013年 | 611篇 |
2012年 | 495篇 |
2011年 | 633篇 |
2010年 | 379篇 |
2009年 | 265篇 |
2008年 | 444篇 |
2007年 | 484篇 |
2006年 | 515篇 |
2005年 | 426篇 |
2004年 | 367篇 |
2003年 | 414篇 |
2002年 | 315篇 |
2001年 | 213篇 |
2000年 | 186篇 |
1999年 | 132篇 |
1998年 | 76篇 |
1997年 | 39篇 |
1996年 | 31篇 |
1995年 | 37篇 |
1994年 | 25篇 |
1993年 | 29篇 |
1992年 | 23篇 |
1991年 | 36篇 |
1990年 | 29篇 |
1989年 | 26篇 |
1988年 | 29篇 |
1987年 | 29篇 |
1986年 | 23篇 |
1985年 | 50篇 |
1984年 | 39篇 |
1983年 | 31篇 |
1982年 | 32篇 |
1981年 | 21篇 |
1980年 | 25篇 |
1979年 | 38篇 |
1978年 | 36篇 |
1977年 | 25篇 |
1973年 | 21篇 |
1972年 | 20篇 |
1952年 | 40篇 |
排序方式: 共有9082条查询结果,搜索用时 15 毫秒
1.
2.
Barbora Straková Michail Rovatsos Lukáš Kubička Lukáš Kratochvíl 《BioEssays : news and reviews in molecular, cellular and developmental biology》2020,42(10):2000050
Frequent independent origins of environmental sex determination (ESD) are assumed within amniotes. However, the phylogenetic distribution of sex-determining modes suggests that ESD is likely very ancient and may be homologous across ESD groups. Sex chromosomes are demonstrated to be old and stable in endothermic (mammals and birds) and many ectothermic (non-avian reptiles) lineages, but they are mostly non-homologous between individual amniote lineages. The phylogenetic pattern may be explained by ancestral ESD with multiple transitions to later evolutionary stable genotypic sex determination. It is pointed out here that amniote ESD shares several key aspects with sequential hermaphroditism of fishes such as a lack of sex differences in genomes, biased population sex ratios, and potentially also molecular mechanism related to general stress responses. Here, it is speculated that ESD evolves via a heterochronic shift of the sensitive period of sex change from the adult to the embryonic stage in a hermaphroditic amniote ancestor. Also see the video abstract here https://youtu.be/q2mjtlCefu4 . 相似文献
3.
4.
Calcium channel blockers, verapamil, nitrendipin and nifedipin, and cyclosporin A inhibited growth of colonies ofBotrytis cinerea in a concentration-dependent manner and simultaneously induced morphological changes of its hyphal tips. Exogenous calcium
at the concentration of 100 mmol/L decreased the growth-inhibitory effects of channel blockers and cyclosporin A; however,
at the concentration of 500 mmol/L Ca2+ their inhibitory effects were increased. At the latter concentration, calcium partly reversed the morphogenic effects of
the blockers but not of cyclosporin A. 相似文献
5.
Jaroslav Dršata Martin Beránek VladimÍr Palička 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):31-36
Incubation of 50 mM d -glucose with aspartate aminotransferase (AST, EC 2.6.1.1) preparations (purified pig heart enzyme or a rat liver 20,000 × g supernatant) at 25°C had no effect on enzyme activity. 50 mM d -fructose or d -ribose gradually inhibited pig heart AST under the same conditions to zero activity after 14 days. 50 mM dl -glyceraldehyde decreased enzyme activity to zero after 6 days of incubation. The inhibition of pig heart AST by 50 mM d -fructose or d -ribose was marked even at a temperature of 4°C but it was less pronounced than at 25°C. There was no effect of 0.5 mM 2-oxoglutarate on AST activity during incubation, while the presence of 25 mM l -aspartate decreased it rapidly. 0.5 mM 2-oxoglutarate partly prevented inhibition of AST by d -ribose or d -fructose, while an analogous experiment with 25 mM aspartate resulted in a rapid decline similar to that in the absence of sugars. 相似文献
6.
Růžička 《Development genes and evolution》1918,43(3):407-407
Ohne Zusammenfassung 相似文献
7.
8.
Hilda Ritter-Studnička 《Plant Systematics and Evolution》1958,105(4):285-292
Zusammenfassung In der vorliegenden Arbeit wurden Pflanzenarten besprochen, die selten oder neu für das Gebiet Bosniens und der Herzegowina, und meist von allgemeinem pflanzengeographischem Interesse sind. Einige dieser Funde wurden auf Dolomit oder Serpentinunterlage festgestellt, von welchen auch einige neue Sippen beschrieben wurden. 相似文献
9.
10.
Rafał Krętowski Anna Stypułkowska Marzanna Cechowska-Pasko 《Molecular and cellular biochemistry》2015,398(1-2):165-173
The inhibition of the 26S proteasome evokes endoplasmic reticulum stress, which has been shown to be implicated in the antitumoral effects of proteasome inhibitors. The cellular and molecular effects of the proteasome inhibitor—bortezomib—on human colon cancer cells are as yet poorly characterized. Bortezomib selectively induces apoptosis in some cancer cells. However, the nature of its selectivity remains unknown. Previously, we demonstrated that, in contrast to normal fibroblasts, bortezomib treatment evoked strong effect on apoptosis of breast cancer cells incubated in hypoxic and normoxic conditions. The study presented here provides novel information on the cellular effects of bortezomib in DLD-1 colon cancer cells line. We observe twofold higher percentage of apoptotic cells incubated for 48 h with 25 and 50 nmol/l of bortezomib in hypoxic conditions and four-, fivefold increase in normoxic conditions in comparison to control cells, incubated without bortezomib. It is of interest that bortezomib evokes strong effect on necrosis of DLD-1 colon cancer cell line. We observe the sixfold increase in necrosis of DLD-1 cells incubated with 25 or 50 nmol/l of bortezomib for 48 h in hypoxia and fourfold increase in normoxic conditions in comparison to adequate controls. We suggest that bortezomib may be candidates for further evaluation as chemotherapeutic agents for human colon cancer. 相似文献