全文获取类型
收费全文 | 19358篇 |
免费 | 1880篇 |
国内免费 | 11篇 |
出版年
2023年 | 83篇 |
2022年 | 217篇 |
2021年 | 398篇 |
2020年 | 195篇 |
2019年 | 266篇 |
2018年 | 322篇 |
2017年 | 263篇 |
2016年 | 473篇 |
2015年 | 870篇 |
2014年 | 866篇 |
2013年 | 1096篇 |
2012年 | 1403篇 |
2011年 | 1355篇 |
2010年 | 901篇 |
2009年 | 729篇 |
2008年 | 1045篇 |
2007年 | 1106篇 |
2006年 | 1045篇 |
2005年 | 1007篇 |
2004年 | 981篇 |
2003年 | 905篇 |
2002年 | 921篇 |
2001年 | 192篇 |
2000年 | 143篇 |
1999年 | 199篇 |
1998年 | 255篇 |
1997年 | 187篇 |
1996年 | 162篇 |
1995年 | 153篇 |
1994年 | 154篇 |
1993年 | 161篇 |
1992年 | 130篇 |
1991年 | 131篇 |
1990年 | 142篇 |
1989年 | 129篇 |
1988年 | 126篇 |
1987年 | 128篇 |
1986年 | 107篇 |
1985年 | 119篇 |
1984年 | 140篇 |
1983年 | 155篇 |
1982年 | 160篇 |
1981年 | 133篇 |
1980年 | 119篇 |
1979年 | 80篇 |
1978年 | 104篇 |
1977年 | 92篇 |
1976年 | 82篇 |
1975年 | 76篇 |
1974年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
A new species,Acanthocephaloides cyrusi, is described from the fishesSolea bleekeri andPomadasys commersoni from Lake St. Lucia, Natal, South Africa. It is distinguished from the other species in the genus by the more marked sexual dimorphism in length, the arrangement of hooks, the proboscis with the longest hooks at the anterior-most extremity and the greater size of the proboscis hooks and body spines. An acanthella, which may represent this species, was found in the tanaidApseudes digitalis. 相似文献
23.
Mary Margaret Huizinga Sara N. Bleich Mary Catherine Beach Jeanne M. Clark Lisa A. Cooper 《Obesity (Silver Spring, Md.)》2010,18(10):1932-1937
Physician perception of medication adherence may alter prescribing patterns. Perception of patients has been linked to readily observable factors, such as race and age. Obesity shares a similar stigma to these factors in society. We hypothesized that physicians would perceive patients with a higher BMI as nonadherent to medication. Data were collected from the baseline visit of a randomized clinical trial of patient–physician communication (240 patients and 40 physicians). Physician perception of patient medication adherence was measured on a Likert scale and dichotomized as fully adherent or not fully adherent. BMI was the predictor of interest. We performed Poisson regression analyses with robust variance estimates, adjusting for clustering of patients within physicians, to examine the association between BMI and physician perception of medication adherence. The mean (s.d.) BMI was 32.6 (7.7) kg/m2. Forty‐five percent of patients were perceived as nonadherent to medications by their physicians. Higher BMI was significantly and negatively associated with being perceived as adherent to medication (prevalence ratio (PrR) 0.76, 95% confidence interval (CI): 0.64–0.90; P = 0.002; per 10 kg/m2 increase in BMI). BMI remained significantly and negatively associated with physician perception of medication adherence after adjustment for patient and physician characteristics (PrR 0.80, 95% CI: 0.66–0.96; P = 0.020). In this study, patients with higher BMI were less likely to be perceived as adherent to medications by their providers. Physician perception of medication adherence has been shown to affect prescribing patterns in other studies. More work is needed to understand how this perception may affect the care of patients with obesity. 相似文献
24.
25.
Lois B. Epstein Mary E. Rose Nancy H. McManus 《Biochemical and biophysical research communications》1982,104(1):341-346
A comparison of the amino acid sequence of one human recombinant IFN-α (IFLrA) with either human β-endorphin or ACTH reveals only a minimal and insignificant degree of homology. Also, synthetic ACTH, β-endorphin and β-endorphin-(1–15) have no antiviral protective effects on human fibroblasts and cannot inhibit the neutralization of the antiviral effects of natural IFN-α by an antiserum directed against the interferon. Anti ACTH and Anti β-endorphin do not neutralize the antiviral effects of IFLrA, and radioimmunoassays of partially purified natural IFN-α and pure IFLrA do not reveal any evidence of α-MSH or β-endorphin-like material in the interferons. These results demonstrate an absence of functional and structural homology of natural and recombinant IFN-α with ACTH and β-endorphin. 相似文献
26.
27.
28.
29.
30.
Kathryn S. Evans Janneke Wit Lewis Stevens Steffen R. Hahnel Briana Rodriguez Grace Park Mostafa Zamanian Shannon C. Brady Ellen Chao Katherine Introcaso Robyn E. Tanny Erik C. Andersen 《PLoS pathogens》2021,17(3)
Parasitic nematodes cause a massive worldwide burden on human health along with a loss of livestock and agriculture productivity. Anthelmintics have been widely successful in treating parasitic nematodes. However, resistance is increasing, and little is known about the molecular and genetic causes of resistance for most of these drugs. The free-living roundworm Caenorhabditis elegans provides a tractable model to identify genes that underlie resistance. Unlike parasitic nematodes, C. elegans is easy to maintain in the laboratory, has a complete and well annotated genome, and has many genetic tools. Using a combination of wild isolates and a panel of recombinant inbred lines constructed from crosses of two genetically and phenotypically divergent strains, we identified three genomic regions on chromosome V that underlie natural differences in response to the macrocyclic lactone (ML) abamectin. One locus was identified previously and encodes an alpha subunit of a glutamate-gated chloride channel (glc-1). Here, we validate and narrow two novel loci using near-isogenic lines. Additionally, we generate a list of prioritized candidate genes identified in C. elegans and in the parasite Haemonchus contortus by comparison of ML resistance loci. These genes could represent previously unidentified resistance genes shared across nematode species and should be evaluated in the future. Our work highlights the advantages of using C. elegans as a model to better understand ML resistance in parasitic nematodes. 相似文献