全文获取类型
收费全文 | 3631篇 |
免费 | 163篇 |
国内免费 | 4篇 |
出版年
2023年 | 31篇 |
2022年 | 39篇 |
2021年 | 105篇 |
2020年 | 69篇 |
2019年 | 81篇 |
2018年 | 123篇 |
2017年 | 83篇 |
2016年 | 97篇 |
2015年 | 154篇 |
2014年 | 198篇 |
2013年 | 276篇 |
2012年 | 302篇 |
2011年 | 263篇 |
2010年 | 199篇 |
2009年 | 169篇 |
2008年 | 175篇 |
2007年 | 164篇 |
2006年 | 140篇 |
2005年 | 140篇 |
2004年 | 127篇 |
2003年 | 105篇 |
2002年 | 107篇 |
2001年 | 60篇 |
2000年 | 48篇 |
1999年 | 50篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 25篇 |
1995年 | 14篇 |
1994年 | 24篇 |
1993年 | 10篇 |
1992年 | 29篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 31篇 |
1988年 | 26篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 19篇 |
1984年 | 22篇 |
1983年 | 9篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 22篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1970年 | 6篇 |
排序方式: 共有3798条查询结果,搜索用时 62 毫秒
1.
Background
Substituted catechols are important precursors for large-scale synthesis of pharmaceuticals and other industrial products. Most of the reported chemical synthesis methods are expensive and insufficient at industrial level. However, biological processes for production of substituted catechols could be highly selective and suitable for industrial purposes. 相似文献2.
The influence of age, weaning, season of the year and body weight on the peripheral levels of progesterone, oestradiol-17β and luteinizing hormone (LH) were studied during neonatal, perinatal and peripubertal periods in buffalo heifers. The buffalo heifers exhibited oestrus only after 30 months of age and had higher levels of LH and oestradiol-17β and a lower level of progesterone on the day of oestrus. The progesterone concentration was affected significantly (P < 0.01) by different seasons, by weaning (P < 0.05) and varied between pubertal and neonatal periods (P < 0.01), whereas the oestradiol-17β level was affected significantly (P < 0.01) by weaning and varied at different seasons and with body weight. However, the LH concentration was greater during the neonatal period than the pre- and peripubertal periods and changed significantly (P < 0.01) between groups of ages and body weights. The results suggest that increases in the levels of oestradiol-17β and progesterone after 30 months of age are probably indicative of the onset of puberty in buffalo heifers. However, a further increase in oestradiol-17β, LH, and a decrease in progesterone are essential for oestrus and cyclicity to be exhibited in buffalo heifers. 相似文献
3.
Shashank Hambarde Chi-Lin Tsai Raj K. Pandita Albino Bacolla Anirban Maitra Vijay Charaka Clayton R. Hunt Rakesh Kumar Oliver Limbo Remy Le Meur Walter J. Chazin Susan E. Tsutakawa Paul Russell Katharina Schlacher Tej K. Pandita John A. Tainer 《Molecular cell》2021,81(14):2989-3006.e9
- Download : Download high-res image (222KB)
- Download : Download full-size image
4.
A survey of cultivated heirloom tomato varieties identifies four new mutant alleles at the green-flesh locus 总被引:1,自引:0,他引:1
Cornelius S. Barry Priyanka Pandey 《Molecular breeding : new strategies in plant improvement》2009,24(3):269-276
The process of crop domestication occurs through the selection and subsequent propagation of novel alleles that improve traits
of interest. Cultivated tomato (Solanum lycopersicum), particularly heirloom varieties, exhibit a wide range of variation in fruit size, shape and color. The green-flesh mutant of tomato possesses a stay-green phenotype resulting in fruits that ripen to a red-brown color, due to the retention
of chlorophyll and the simultaneous accumulation of lycopene. The recent identification of the GREEN-FLESH gene provides a molecular tool with which to investigate the origin of a subset of cultivated tomato varieties that resemble
the green-flesh mutant. Sequence analysis of the GF locus from 26 varieties revealed the existence of four previously unidentified null alleles. This study illustrates the potential
of cultivated tomato varieties, including heritage cultivars, heirlooms, and land races, for uncovering new alleles in genes
of interest. 相似文献
5.
Sandhya Ravishankar Meera Pandey R. P. Tewari V. Krishna 《World journal of microbiology & biotechnology》2006,22(10):1021-1025
Summary The sporophores of Pleurotus are gymnocarpous and continuously release spores in the atmosphere causing respiratory allergies like hay fever and farmer’s lung disease among workers. The allergy is caused by the antigens present on the walls of the spores. Apart from this, during commercial production, these spores settle on the fruit bodies, germinate and form a velvety film which gives an unpleasant appearance to the mushrooms. The spores emitted may include new genotypes likely to attack wood or trees. Spore allergy is one of the most important limiting factors for the large scale cultivation of this species. Different approaches are being adopted at IIHR for the production of commercial sporeless/low-sporing strains of Pleurotus to alleviate the spore allergy problem. Attempts were made during the present investigation to produce sporeless or low-sporing mutants through u.v. mutation. Mutation of the mycelium did not yield the desired results. Mutation of the spores of Pleurotus sajor-caju yielded an extremely low-sporing mutant after 75 min exposure. The character has been found to be stable for more than 10 generations of subculturing. 相似文献
6.
Emily Olfson Catherine E. Cottrell Nicholas O. Davidson Christina A. Gurnett Jonathan W. Heusel Nathan O. Stitziel Li-Shiun Chen Sarah Hartz Rakesh Nagarajan Nancy L. Saccone Laura J. Bierut 《PloS one》2015,10(9)
The American College of Medical Genetics and Genomics (ACMG) recommends that clinical sequencing laboratories return secondary findings in 56 genes associated with medically actionable conditions. Our goal was to apply a systematic, stringent approach consistent with clinical standards to estimate the prevalence of pathogenic variants associated with such conditions using a diverse sequencing reference sample. Candidate variants in the 56 ACMG genes were selected from Phase 1 of the 1000 Genomes dataset, which contains sequencing information on 1,092 unrelated individuals from across the world. These variants were filtered using the Human Gene Mutation Database (HGMD) Professional version and defined parameters, appraised through literature review, and examined by a clinical laboratory specialist and expert physician. Over 70,000 genetic variants were extracted from the 56 genes, and filtering identified 237 variants annotated as disease causing by HGMD Professional. Literature review and expert evaluation determined that 7 of these variants were pathogenic or likely pathogenic. Furthermore, 5 additional truncating variants not listed as disease causing in HGMD Professional were identified as likely pathogenic. These 12 secondary findings are associated with diseases that could inform medical follow-up, including cancer predisposition syndromes, cardiac conditions, and familial hypercholesterolemia. The majority of the identified medically actionable findings were in individuals from the European (5/379) and Americas (4/181) ancestry groups, with fewer findings in Asian (2/286) and African (1/246) ancestry groups. Our results suggest that medically relevant secondary findings can be identified in approximately 1% (12/1092) of individuals in a diverse reference sample. As clinical sequencing laboratories continue to implement the ACMG recommendations, our results highlight that at least a small number of potentially important secondary findings can be selected for return. Our results also confirm that understudied populations will not reap proportionate benefits of genomic medicine, highlighting the need for continued research efforts on genetic diseases in these populations. 相似文献
7.
A K Srivastava C Pandey K P Dwivedi V K Singh 《Indian journal of biochemistry & biophysics》1989,26(3):199-200
QSAR studies have been performed on the homologues of 3-triazines, using molecular connectivity index and van der Waal volume as structural parameters. The regression analysis has shown good correlation between antitumour activity and the two structural parameters. 相似文献
8.
9.
Mutations with respect to the sporulating character in the cyanobacteriumAnabaena doliolum (AdS and AdB strains) were induced after treatment with acriflavin, acridine organge 9-aminoacridine, N-methyl-N′-nitro-N-nitrosoguanidine,
ethyl methanesulfonate, hydroxylamine, nitrous acid, low pH (pH 4.2) and elevated temperature (65±1 °C). Exposure to higher
temperature was most effective in inducing nonsporulating mutants in both strains. Uptake of acridine dyes, inactivation and
mutability with respect to sporulation of two strains of cyanobacteriumA. doliolum revealed that the mutagen uptake could be directly correlated with the frequency of induced mutations but that survival and
mutability are independent strain-specific properties. 相似文献
10.
Jyotsana Prakash Rakesh Sharma Subhasree Ray Shikha Koul Vipin Chandra Kalia 《Indian journal of microbiology》2018,58(2):127-137
Wastewaters are a rich source of nutrients for microorganisms. However, if left unattended the biodegradation may lead to severe environmental hazards. The wastewaters can thus be utilized for the production of various value added products including bioenergy (H2 and CH4). A number of studies have reported utilization of various wastewaters for energy production. Depending on the nature of the wastewater, different reactor configurations, wastewater and inoculum pretreatments, co-substrate utilizations along with other process parameters have been studied for efficient product formation. Only a few studies have reported sequential utilization of wastewaters for H2 and CH4 production despite its huge potential for complete waste degradation. 相似文献