全文获取类型
收费全文 | 3358篇 |
免费 | 416篇 |
国内免费 | 1篇 |
出版年
2021年 | 35篇 |
2019年 | 30篇 |
2018年 | 34篇 |
2017年 | 28篇 |
2016年 | 55篇 |
2015年 | 90篇 |
2014年 | 86篇 |
2013年 | 133篇 |
2012年 | 145篇 |
2011年 | 144篇 |
2010年 | 85篇 |
2009年 | 98篇 |
2008年 | 125篇 |
2007年 | 127篇 |
2006年 | 113篇 |
2005年 | 108篇 |
2004年 | 95篇 |
2003年 | 109篇 |
2002年 | 88篇 |
2001年 | 90篇 |
2000年 | 103篇 |
1999年 | 87篇 |
1998年 | 41篇 |
1997年 | 45篇 |
1996年 | 54篇 |
1995年 | 36篇 |
1994年 | 42篇 |
1993年 | 53篇 |
1992年 | 82篇 |
1991年 | 87篇 |
1990年 | 92篇 |
1989年 | 72篇 |
1988年 | 37篇 |
1987年 | 58篇 |
1986年 | 60篇 |
1985年 | 79篇 |
1984年 | 51篇 |
1983年 | 52篇 |
1982年 | 46篇 |
1981年 | 40篇 |
1980年 | 52篇 |
1979年 | 49篇 |
1978年 | 41篇 |
1977年 | 42篇 |
1975年 | 51篇 |
1974年 | 36篇 |
1973年 | 40篇 |
1972年 | 32篇 |
1971年 | 28篇 |
1970年 | 29篇 |
排序方式: 共有3775条查询结果,搜索用时 15 毫秒
21.
The healthcare of people with HIV is transitioning from specialty care to the primary healthcare (PHC) system. However, many of the performance indicators used to measure the quality of HIV care pre-date this transition. The goal of this work was to examine how existing HIV care performance indicators measure the comprehensive and longitudinal care offered in a PHC setting. A scoping review consisting of peer-reviewed and grey literature searches was performed. Two reviewers evaluated study eligibility and indicators in documents meeting inclusion criteria were extracted into a database. Indicators were matched to a PHC performance measurement framework to determine their applicability for evaluating quality of care in the PHC setting. The literature search identified 221 publications, of which 47 met inclusion criteria. 1184 indicators were extracted and removal of duplicates left 558 unique indicators. A majority of the 558 indicators fell under the ‘secondary prevention’ (12%) and ‘care of chronic conditions’ (33%) domains when indicators were matched to the PHC performance framework. Despite the imbalance, nearly all performance domains in the PHC framework were populated by at least one indicator with significant concentrations in domains such as patient-provider relationship, patient satisfaction, population and community characteristics, and access to care. Existing performance frameworks for the care of people with HIV provide a comprehensive set of indicators that align well with a PHC performance framework. Nonetheless, some important elements of care, such as patient-reported outcomes, are poorly covered by existing indicators. Advancing our understanding of how the experience of care for people with HIV is impacted by changes in health services delivery, specifically more care within the PHC system, will require performance indicators to capture this aspect of HIV care. 相似文献
22.
Bacterial lipopolysaccharide (LPS) blotted to polyvinylidene difluoride (PVDF) membranes was detected by a technique adapted from current methodologies used to detect glycoproteins. PVDF-bound LPS was coupled to a hapten and localized on the membrane by Western blotting with an antibody-alkaline phosphatase conjugate specific for the hapten. Immobilon blots could be made reversibly transparent for photography and densitometry. 相似文献
23.
In the presence of a halobenzene or benzonitrile, Pseudomonas T-12 can produce substituted catechols from the corresponding substituted benzenes. A variety of monosubstituted benzenes with substituents containing up to four carbons, and some meta- and para- disubstituted benzenes, can serve as catechol precursors. 相似文献
24.
25.
26.
A R Yobs A E Plott M D Hicklin S A Coleman W W Johnston P R Ashton I F Rube J C Watts Z M Naib R J Wood 《Acta cytologica》1987,31(6):900-910
Two laboratories exchanged and rescreened a large sample of cases with cervicovaginal smears they had consecutively accessioned to examine the reproducibility of gynecologic cytodiagnosis under optimum conditions. At least a "working agreement" (diagnoses within +/- 1 category on a ten-category scale) was achieved in diagnoses of normal, benign reaction and squamous abnormality (from minimal dysplasia though invasive cancer) in 18,859 cases (96.8%), of endometrial abnormality in 21 cases (42%) and of "unsatisfactory" in 99 cases (20.7%). Larger differences occurred in greater than or equal to 30% of cases except in the categories of "normal" and "benign reaction," reaching a maximum of 82% for moderate dysplasia. Reexamining 382 cases decreased disagreement by category to the 20% to 65% range only in the five categories of dysplasia plus carcinoma in situ. Agreement was not predicated on the presence of endocervical cells or squamous metaplasia; the basis for "unsatisfactory" calls was not uniform. Comparison of the laboratories' diagnoses with referee diagnoses or, on 178 cases, with tissue diagnoses also demonstrated differences in diagnostic criteria. 相似文献
27.
Palmitic acid specifically deuterated at different carbon atoms, has been incorporated biosynthetically into the membrane lipids of Clostridium butyricum. The lipids of this organism are rich in plasmalogens and their glycerol acetals and exhibit an unusual fatty acyl and alkenyl chain distribution with saturated chains mainly at the sn-2 position and unsaturated chains at the sn-1 position. The ordering of the deuterated hydrocarbon chains in whole cells was measured with deuterium nuclear magnetic resonance and was compared to the order profiles of isolated cell membranes and membranes formed from the total phospholipid extract. The shape of the order profiles was similar for all three membranes, but the absolute values of the order profiles in whole cells and isolated membranes were lower than those of the liposomal lipids. The order profiles have the same characteristic shape as those found for the lamellar liquid-crystalline phases of synthetic diacylphospholipids. 相似文献
28.
Antisera elicited by immunization of rabbits with 4'-aminomethyl-trioxsalen (AMT)-modified poly(A,U) complexed with methylated bovine serum albumin was characterized in competition radioimmunoassays (RIA) and enzyme-linked immunosorbent assays (ELISA). AMT-poly(A,U) was over 10,000-fold more reactive than unmodified poly(A,U) or AMT alone. The antiserum cross-reacted to varying extents with AMT-modified-RNA's and -DNA's. The presence of AMT-uridine usually assured strong reactivity. The amino group of AMT contributed to antibody binding to a small degree. Binding was not significantly affected by high ionic strength, suggesting that binding does not involve ion pair formation. Murine encephalomyocarditis virus replicative intermediates, as well as cellular RNA and DNA were modified by psoralen in intact cells, suggesting that EMCV RNA and cellular RNA's in intact cells possess detectable stretches of base pairs. The antibodies described here will be useful in studying the secondary and tertiary structure of RNA's in vitro and in intact cells. 相似文献
29.
30.
J Hadidian S R Jenkins D H Johnston P J Savarie V F Nettles D Manski G M Baer 《Journal of wildlife diseases》1989,25(1):1-9
In summer 1986, a study was conducted to evaluate raccoon (Procyon lotor) acceptance of oral baits that could be used for rabies vaccination. One thousand wax-coated sponge bait cubes were filled with 5 mg of a seromarker (iophenoxic acid), placed in polyethylene bags, and hand-distributed in an 80 ha area within an urban National Park in Washington, D. C. (USA). After 3 wk, target and nontarget animals were trapped and blood samples collected to evaluate bait uptake. Thirty-three of 52 (63%) raccoons had elevated blood iodine levels indicating they had eaten at least one bait, 13 (25%) were negative, and six (12%) had marginal values. These results indicate that sponge baits hand-placed at a density of 12.4/ha can reach a significant proportion of an urban raccoon population. Implications for oral rabies vaccination of raccoons are discussed. 相似文献