全文获取类型
收费全文 | 8518篇 |
免费 | 487篇 |
国内免费 | 6篇 |
出版年
2023年 | 70篇 |
2022年 | 63篇 |
2021年 | 217篇 |
2020年 | 150篇 |
2019年 | 168篇 |
2018年 | 233篇 |
2017年 | 214篇 |
2016年 | 272篇 |
2015年 | 353篇 |
2014年 | 404篇 |
2013年 | 562篇 |
2012年 | 578篇 |
2011年 | 550篇 |
2010年 | 335篇 |
2009年 | 275篇 |
2008年 | 388篇 |
2007年 | 347篇 |
2006年 | 335篇 |
2005年 | 333篇 |
2004年 | 270篇 |
2003年 | 223篇 |
2002年 | 228篇 |
2001年 | 200篇 |
2000年 | 179篇 |
1999年 | 163篇 |
1998年 | 58篇 |
1997年 | 55篇 |
1996年 | 65篇 |
1995年 | 52篇 |
1994年 | 59篇 |
1993年 | 37篇 |
1992年 | 117篇 |
1991年 | 117篇 |
1990年 | 88篇 |
1989年 | 95篇 |
1988年 | 88篇 |
1987年 | 89篇 |
1986年 | 86篇 |
1985年 | 90篇 |
1984年 | 80篇 |
1983年 | 50篇 |
1982年 | 48篇 |
1981年 | 43篇 |
1980年 | 48篇 |
1979年 | 78篇 |
1978年 | 58篇 |
1977年 | 50篇 |
1976年 | 42篇 |
1974年 | 39篇 |
1973年 | 44篇 |
排序方式: 共有9011条查询结果,搜索用时 15 毫秒
1.
Aruna S. Jaiswal Harekrushna Panda Brian K. Law Jay Sharma Jitesh Jani Robert Hromas Satya Narayan 《PloS one》2015,10(5)
Recently approved chemotherapeutic agents to treat colorectal cancer (CRC) have made some impact; however, there is an urgent need for newer targeted agents and strategies to circumvent CRC growth and metastasis. CRC frequently exhibits natural resistance to chemotherapy and those who do respond initially later acquire drug resistance. A mechanism to potentially sensitize CRC cells is by blocking the DNA polymerase β (Pol-β) activity. Temozolomide (TMZ), an alkylating agent, and other DNA-interacting agents exert DNA damage primarily repaired by a Pol-β-directed base excision repair (BER) pathway. In previous studies, we used structure-based molecular docking of Pol-β and identified a potent small molecule inhibitor (NSC666715). In the present study, we have determined the mechanism by which NSC666715 and its analogs block Fen1-induced strand-displacement activity of Pol-β-directed LP-BER, cause apurinic/apyrimidinic (AP) site accumulation and induce S-phase cell cycle arrest. Induction of S-phase cell cycle arrest leads to senescence and apoptosis of CRC cells through the p53/p21 pathway. Our initial findings also show a 10-fold reduction of the IC50 of TMZ when combined with NSC666715. These results provide a guide for the development of a target-defined strategy for CRC chemotherapy that will be based on the mechanisms of action of NSC666715 and TMZ. This combination strategy can be used as a framework to further reduce the TMZ dosages and resistance in CRC patients. 相似文献
2.
This study was conducted to study the long-term impact of bioinoculants, Azotobacter chroococcum and arbuscular mycorrhizal fungi (AMF) on growth and biomass yield of Jatropha curcas grown in nursery and in field conditions. The experiment was set up in a randomized block design, and the following treatments was designed (T1 = control, T2 = Azotobacter, T3 = inoculation with AMF, and T4 = inoculation with Azotobacter + AMF). Data on various growth attributes (shoot height and shoot diameter) and biochemical parameters [leaf relative water content (LRWC), sugars, protein, and photosynthetic pigments] were recorded up to 6 months in the nursery and in the field (18 months). Results pertaining to morpho-physiological traits showed Azotobacter and AMF consortia increase shoot height, shoot diameter, LRWC, sugars, proteins, and photosynthetic pigments over control under nursery conditions. Besides enhancing the plant growth, these bioinoculants helped in better establishment of Jatropha plants under field conditions. A significant improvement in the shoot height, shoot diameter, fruit yield/plant, and seed yield (g)/plant was evident in 18-month-old Jatropha plants under field conditions when Azotobacter and AMF were co-inoculated. This work supports the application of bioinoculants for establishment of Jatropha curcas in semi-arid regions. 相似文献
3.
4.
5.
E. Rai S. Sharma A. Koul A. K. Bhat A. J. S. Bhanwer R. N. K. Bamezai 《Human genetics》2008,123(1):117
6.
Yogeeta O. Agrawal Pankaj Kumar Sharma Birendra Shrivastava Shreesh Ojha Harshita M. Upadhya Dharamvir Singh Arya Sameer N. Goyal 《PloS one》2014,9(11)
The present study investigated the effect of hesperidin, a natural flavonoid, in cardiac ischemia and reperfusion (I/R) injury in diabetic rats. Male Wistar rats with diabetes were divided into five groups and were orally administered saline once daily (IR-sham and IR-control), Hesperidin (100 mg/kg/day; IR-Hesperidin), GW9962 (PPAR-γ receptor antagonist), or combination of both for 14 days. On the 15th day, in the IR-control and IR-treatment groups, rats were subjected to left anterior descending (LAD) coronary artery occlusion for 45 minutes followed by a one-hour reperfusion. Haemodynamic parameters were recorded and rats were sacrificed; hearts were isolated for biochemical, histopathological, ultrastructural and immunohistochemistry. In the IR-control group, significant ventricular dysfunctions were observed along with enhanced expression of pro-apoptotic protein Bax. A decline in cardiac injury markers lactate dehydrogenase activity, CK-MB and increased content of thiobarbituric acid reactive substances, a marker of lipid peroxidation, and TNF-α were observed. Hesperidin pretreatment significantly improved mean arterial pressure, reduced left ventricular end-diastolic pressure, and improved both inotropic and lusitropic function of the heart (+LVdP/dt and –LVdP/dt) as compared to IR-control. Furthermore, hesperidin treatment significantly decreased the level of thiobarbituric acid reactive substances and reversed the activity of lactate dehydrogenase towards normal value. Hesperidin showed anti-apoptotic effects by upregulating Bcl-2 protein and decreasing Bax protein expression. Additionally, histopathological and ultrastructural studies reconfirmed the protective action of hesperidin. On the other hand, GW9662, selective PPAR-γ receptor antagonist, produced opposite effects and attenuated the hesperidin induced improvements. The study for the first time evidence the involvement of PPAR-γ pathway in the cardioprotective activity of hesperidin in I/R model in rats. 相似文献
7.
Richard Serianni Jed Barash Timothy Bentley Pushpa Sharma John L Fontana Darin Via Jochen Duhm Rolf Bunger Paul D Mongan 《Journal of applied physiology》2003,94(2):561-566
The determination of O(2) consumption by using arteriovenous O(2) content differences is dependent on accurate oxyhemoglobin saturation measurements. Because swine are a common experimental species, we describe the validation of CO-oximeter for porcine-specific oxyhemoglobin saturation. After developing a nonlinear mathematical model of the porcine oxyhemoglobin saturation curve, we made 366 porcine oxyhemoglobin saturation determinations with a calibrated blood-gas analyzer and a porcine-specific CO-oximeter. There was a high degree of correlation with minimal variability (r(2) = 0.99, SE of the estimate = 5.2%) between the mathematical model and the porcine-specific CO-oximeter measurements. Bland-Altman comparison showed that the CO-oximeter measurements were biased slightly lower (-0.4 vol%), and the limits of agreement (+/-2 SD) were 0.7 and -1.5 vol%. This is in contrast to a 10-20 vol% error if human-specific methods were used. The results show excellent agreement between the nonlinear model and CO-oximeter for porcine-specific oxyhemoglobin saturation measurements. In contrast, comparison of the porcine-specific oxyhemoglobin saturations with saturations obtained by using human methods highlights the necessity of species-specific measurement methodology. 相似文献
8.
Om P Sharma 《BMJ (Clinical research ed.)》1999,319(7223):1468
9.
10.