全文获取类型
收费全文 | 6895篇 |
免费 | 585篇 |
国内免费 | 440篇 |
出版年
2024年 | 12篇 |
2023年 | 87篇 |
2022年 | 204篇 |
2021年 | 346篇 |
2020年 | 218篇 |
2019年 | 253篇 |
2018年 | 288篇 |
2017年 | 184篇 |
2016年 | 240篇 |
2015年 | 425篇 |
2014年 | 412篇 |
2013年 | 530篇 |
2012年 | 625篇 |
2011年 | 568篇 |
2010年 | 314篇 |
2009年 | 296篇 |
2008年 | 361篇 |
2007年 | 322篇 |
2006年 | 248篇 |
2005年 | 244篇 |
2004年 | 227篇 |
2003年 | 222篇 |
2002年 | 184篇 |
2001年 | 134篇 |
2000年 | 89篇 |
1999年 | 115篇 |
1998年 | 76篇 |
1997年 | 61篇 |
1996年 | 57篇 |
1995年 | 56篇 |
1994年 | 41篇 |
1993年 | 42篇 |
1992年 | 64篇 |
1991年 | 35篇 |
1990年 | 37篇 |
1989年 | 39篇 |
1988年 | 29篇 |
1987年 | 24篇 |
1986年 | 30篇 |
1985年 | 29篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 10篇 |
1971年 | 5篇 |
1954年 | 6篇 |
排序方式: 共有7920条查询结果,搜索用时 15 毫秒
1.
The mechanism of mass collaboration in risk management was studied during the Sichuan earthquake under a Web-based “PeopleFinder” project, where information is contributed and shared among mass contributors. The case study is provided by a great earthquake that happened in Wenchuan County, Sichuan Province, of southwestern China at 2:28 p.m. on May 12, 2008. We witnessed and experienced the rescue and relief efforts for the great earthquake. In this article, two fundamental frameworks are developed to study the mechanism of mass collaboration. Mass collaboration is proven to be effective in a big public crisis such as the Sichuan earthquake. 相似文献
2.
3.
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
4.
Pierre Bongrand Gilles Bouvenot Robert Bartolin J Jeanne Tatossian Bernard Bruguerolle 《Chronobiology international》1988,5(1):81-83
Eleven male subjects were investigated to detect a possible circadian rhythm of the polymorphonuclear phagocytosis. Both cell activity and serum opsonins were studied for numerical detection of granulocytes having ingested at least one particle and for the mean number of ingested particles per cell. No significant temporal differences (ANOVA and cosinor) were found. 相似文献
5.
Females of social Hymenoptera show developmental plasticity in response to varying social and environmental conditions, though some species have strong genetic influences on the form of the female reproductives. In ants, a queen polymorphism can occur in which large queens initiate new colonies on their own, while small queens enter established nests. Most queen polymorphisms studied to date originate due to genetic differences between individuals of differing form. Here, we report on the development of female form in response to social factors within the nest in the queen-polymorphic ant Temnothorax longispinosus. Three queen size morphs occur: a rare large queen with higher fat stores that can found new colonies independently, a large queen that has low fat stores and is behaviorally flexible, and a small queen that rejoins the natal nest. Both in nesting units collected from the field and those reared in the lab, queen presence during larval development led to fewer larvae developing as gynes (virgin, winged queens), and most of those gynes were the small morph. This queen effect is transferred to developing gyne larvae by close, physical interaction between queens and workers, and causes slower larval development. We conclude that gyne size, and therefore reproductive behavior, in T. longispinosus is developmentally plastic in response to queen presence. Plasticity in reproductive behavior may be an adaptive response to the nest sites utilized by this species. T. longispinosus nests predominantly in acorns and hickory nuts, which can vary dramatically from 1 year to the next. Since queens are more likely to be present in each nesting unit when fewer nest sites are available, the queen effect that results in more small gynes produced links the expression of colony-founding traits to ecological conditions across habitat patches. 相似文献
6.
7.
Haiyan Miao Jingjing Lu Yibing Guo Hongquan Qiu Yu Zhang Xihao Yao Xiaohong Li Yuhua Lu 《Journal of cellular and molecular medicine》2021,25(7):3654-3664
Pancreatic ductal adenocarcinoma (PDAC) is an invasive and aggressive cancer that remains a major threat to human health across the globe. Despite advances in cancer treatments and diagnosis, the prognosis of PDAC patients remains poor. New and more effective PDAC therapies are therefore urgently required. In this study, we identified a novel host factor, namely the LncRNA TP73-AS1, as overexpressed in PDAC tissues compared to adjacent healthy tissue samples. The overexpression of TP-73-AS1 was found to correlate with both PDAC stage and lymph node metastasis. To reveal its role in PDCA, we targeted TP73-AS1 using LnRNA inhibitors in a range of pancreatic cancer (PC) cell lines. We found that the inhibition of TP73-AS1 led to a loss of MMP14 expression in PC cells and significantly inhibited their migratory and invasive capacity. No effects of TP73-AS1 on cell survival or proliferation were observed. Mechanistically, we found that TP73-AS1 suppressed the expression of the known oncogenic miR-200a. Taken together, these data highlight the prognostic potential of TP73-AS1 for PC patients and highlight it as a potential anti-PDAC therapeutic target. 相似文献
8.
9.
10.