全文获取类型
收费全文 | 9093篇 |
免费 | 500篇 |
国内免费 | 6篇 |
专业分类
9599篇 |
出版年
2023年 | 75篇 |
2022年 | 126篇 |
2021年 | 257篇 |
2020年 | 155篇 |
2019年 | 173篇 |
2018年 | 247篇 |
2017年 | 222篇 |
2016年 | 282篇 |
2015年 | 375篇 |
2014年 | 427篇 |
2013年 | 601篇 |
2012年 | 617篇 |
2011年 | 584篇 |
2010年 | 358篇 |
2009年 | 287篇 |
2008年 | 412篇 |
2007年 | 375篇 |
2006年 | 359篇 |
2005年 | 357篇 |
2004年 | 300篇 |
2003年 | 238篇 |
2002年 | 250篇 |
2001年 | 204篇 |
2000年 | 182篇 |
1999年 | 169篇 |
1998年 | 74篇 |
1997年 | 56篇 |
1996年 | 72篇 |
1995年 | 54篇 |
1994年 | 65篇 |
1993年 | 41篇 |
1992年 | 118篇 |
1991年 | 119篇 |
1990年 | 91篇 |
1989年 | 96篇 |
1988年 | 91篇 |
1987年 | 90篇 |
1986年 | 89篇 |
1985年 | 94篇 |
1984年 | 83篇 |
1983年 | 51篇 |
1982年 | 49篇 |
1981年 | 42篇 |
1980年 | 49篇 |
1979年 | 79篇 |
1978年 | 58篇 |
1977年 | 49篇 |
1976年 | 42篇 |
1974年 | 39篇 |
1973年 | 44篇 |
排序方式: 共有9599条查询结果,搜索用时 15 毫秒
991.
Abhineet M. Sharma Breanna Baraff John T. Hutchins Michelle K. Wong G. Kai Blaisdell Monica L. Cooper Kent M. Daane Rodrigo P. P. Almeida 《PloS one》2015,10(11)
Some diseases manifest as one characteristic set of symptoms to the host, but can be caused by multiple pathogens. Control treatments based on plant symptoms can make it difficult to effectively manage such diseases, as the biology of the underlying pathogens can vary. Grapevine leafroll disease affects grapes worldwide, and is associated with several viral species in the family Closteroviridae. Whereas some of the viruses associated with this disease are transmitted by insect vectors, others are only graft-transmissible. In three regions of California, we surveyed vineyards containing diseased vines and screened symptomatic plants for all known viral species associated with grapevine leafroll disease. Relative incidence of each virus species differed among the three regions regions, particularly in relation to species with known vectors compared with those only known to be graft-transmitted. In one region, the pathogen population was dominated by species not known to have an insect vector. In contrast, populations in the other surveyed regions were dominated by virus species that are vector-transmissible. Our survey did not detect viruses associated with grapevine leafroll disease at some sites with characteristic disease symptoms. This could be explained either by undescribed genetic diversity among these viruses that prevented detection with available molecular tools at the time the survey was performed, or a misidentification of visual symptoms that may have had other underlying causes. Based on the differences in relative prevalence of each virus species among regions and among vineyards within regions, we expect that region and site-specific management strategies are needed for effective disease control. 相似文献
992.
Neekun Sharma Anthony M. Belenchia Ryan Toedebusch Lakshmi Pulakat Chetan P. Hans 《Journal of cellular and molecular medicine》2020,24(13):7393-7404
Clinical and experimental studies show that angiotensin II (AngII) promotes vascular pathology via activation of AngII type 1 receptors (AT1Rs). We recently reported that NP‐6A4, a selective peptide agonist for AngII type 2 receptor (AT2R), exerts protective effects on human vascular cells subjected to serum starvation or doxorubicin exposure. In this study, we investigated whether NP‐6A4–induced AT2R activation could mitigate AngII‐induced abdominal aortic aneurism (AAA) using AngII‐treated Apoe?/? mice. Male Apoe?/? mice were infused with AngII (1 µg/kg/min) by implanting osmotic pumps subcutaneously for 28 days. A subset of mice was pre‐treated subcutaneously with NP‐6A4 (2.5 mg/kg/day) or vehicle for 14 days prior to AngII, and treatments were continued for 28 days. NP‐6A4 significantly reduced aortic stiffness of the abdominal aorta induced by AngII as determined by ultrasound functional analyses and histochemical analyses. NP‐6A4 also increased nitric oxide bioavailability in aortic tissues and suppressed AngII‐induced increases in monocyte chemotactic protein‐1, osteopontin and proteolytic activity of the aorta. However, NP‐6A4 did not affect maximal intraluminal aortic diameter or AAA incidences significantly. These data suggest that the effects of AT2R agonist on vascular pathologies are selective, affecting the aortic stiffness and proteolytic activity without affecting the size of AAA. 相似文献
993.
Patil Prakash G. Jamma Shivani M. Singh N. V. Bohra Abhishek Parashuram Shilpa Injal Archana S. Gargade Vaishali A. Chakranarayan Manasi G. Salutgi Unnati D. Dhinesh Babu K. Sharma Jyotsana 《Physiology and Molecular Biology of Plants》2020,26(6):1249-1261
Physiology and Molecular Biology of Plants - The present study investigates the genetic diversity and population structure among 42 diverse pomegranate genotypes using a set of twenty one class I... 相似文献
994.
Kaur Jasmeet Akhatar Javed Goyal Anna Kaur Navneet Kaur Snehdeep Mittal Meenakshi Kumar Nitin Sharma Heena Banga Shashi Banga S. S. 《Molecular biology reports》2020,47(4):2963-2974
Molecular Biology Reports - We investigated phenotypic variations for pod shattering, pod length and number of seeds per pod in large germplasm collections of Brassica juncea (2n?=?36;... 相似文献
995.
Kaur Parampreet Jindal Suruchi Yadav Bharat Yadav Inderjit Mahato Ajay Sharma Priti Kaur Satinder Gupta O. P. Vrána Jan Šimková Hana Doležel Jaroslav Gill Bikram Singh Meyer Klaus F. X. Khurana J. P. Singh N. K. Chhuneja Parveen Singh Kuldeep 《Molecular biology reports》2020,47(3):1991-2003
Molecular Biology Reports - Diploid A genome wheat species harbor immense genetic variability which has been targeted and proven useful in wheat improvement. Development and deployment of... 相似文献
996.
997.
998.
Sanjib Das Robindra N. Baruah Ram P. Sharma Jogendra N. Baruah Palaniappan Kulanthaivel Werner Herz 《Phytochemistry》1983,22(9):1989-1991
Cynaropicrin, 11βH-11,13-dihydrodesacylcynaropicrin, aguerins A and B, isoamberboin and the new guaianolides saussureolide and 11βH-11,13-dihydrodesacylcynaropicrin 8-β-d-glucoside were isolated from Saussurea affinis. 相似文献
999.
1000.
Sajad Majeed Zargar Sufia Farhat Reetika Mahajan Ayushi Bhakhri Arjun Sharma 《Saudi Journal of Biological Sciences》2016,23(1):139-149
Increase in food production viz-a-viz quality of food is important to feed the growing human population to attain food as well as nutritional security. The availability of diverse germplasm of any crop is an important genetic resource to mine the genes that may assist in attaining food as well as nutritional security. Here we used 15 RAPD and 23 SSR markers to elucidate diversity among 51 common bean genotypes mostly landraces collected from the Himalayan region of Jammu and Kashmir, India. We observed that both the markers are highly polymorphic. The discriminatory power of these markers was determined using various parameters like; percent polymorphism, PIC, resolving power and marker index. 15 RAPDs produced 171 polymorphic bands, while 23 SSRs produced 268 polymorphic bands. SSRs showed a higher PIC value (0.300) compared to RAPDs (0.243). Further the resolving power of SSRs was 5.241 compared to 3.86 for RAPDs. However, RAPDs showed a higher marker index (2.69) compared to SSRs (1.279) that may be attributed to their higher multiplex ratio. The dendrograms generated with hierarchical UPGMA cluster analysis grouped genotypes into two main clusters with various degrees of sub clustering within the cluster. Here we observed that both the marker systems showed comparable accuracy in grouping genotypes of common bean according to their area of cultivation. The model based STRUCTURE analysis using 15 RAPD and 23 SSR markers identified a population with 3 sub-populations which corresponds to distance based groupings. High level of genetic diversity was observed within the population. These findings have further implications in common bean breeding as well as conservation programs. 相似文献