全文获取类型
收费全文 | 2622篇 |
免费 | 287篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 120篇 |
妇产科学 | 69篇 |
基础医学 | 309篇 |
口腔科学 | 58篇 |
临床医学 | 293篇 |
内科学 | 668篇 |
皮肤病学 | 36篇 |
神经病学 | 181篇 |
特种医学 | 256篇 |
外科学 | 248篇 |
综合类 | 119篇 |
预防医学 | 209篇 |
眼科学 | 19篇 |
药学 | 171篇 |
中国医学 | 7篇 |
肿瘤学 | 178篇 |
出版年
2023年 | 24篇 |
2022年 | 23篇 |
2021年 | 62篇 |
2020年 | 35篇 |
2019年 | 32篇 |
2018年 | 47篇 |
2017年 | 76篇 |
2016年 | 62篇 |
2015年 | 66篇 |
2014年 | 102篇 |
2013年 | 126篇 |
2012年 | 107篇 |
2011年 | 129篇 |
2010年 | 99篇 |
2009年 | 113篇 |
2008年 | 93篇 |
2007年 | 121篇 |
2006年 | 124篇 |
2005年 | 113篇 |
2004年 | 102篇 |
2003年 | 75篇 |
2002年 | 86篇 |
2001年 | 80篇 |
2000年 | 68篇 |
1999年 | 56篇 |
1998年 | 93篇 |
1997年 | 81篇 |
1996年 | 68篇 |
1995年 | 67篇 |
1994年 | 57篇 |
1993年 | 49篇 |
1992年 | 41篇 |
1991年 | 26篇 |
1990年 | 37篇 |
1989年 | 45篇 |
1988年 | 37篇 |
1987年 | 37篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 26篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 18篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 16篇 |
1969年 | 7篇 |
排序方式: 共有2961条查询结果,搜索用时 578 毫秒
81.
82.
A Ingason I Giegling A M Hartmann J Genius B Konte M Friedl Schizophrenia Working Group of the Psychiatric Genomics Consortium S Ripke P F Sullivan D St. Clair D A Collier M C O'Donovan K Mirnics D Rujescu 《Translational psychiatry》2015,5(10):e656
Antagonists of the N-methyl-D-aspartate (NMDA)-type glutamate receptor induce psychosis in healthy individuals and exacerbate schizophrenia symptoms in patients. In this study we have produced an animal model of NMDA receptor hypofunction by chronically treating rats with low doses of the NMDA receptor antagonist MK-801. Subsequently, we performed an expression study and identified 20 genes showing altered expression in the brain of these rats compared with untreated animals. We then explored whether the human orthologs of these genes are associated with schizophrenia in the largest schizophrenia genome-wide association study published to date, and found evidence for association for 4 out of the 20 genes: SF3B1, FOXP1, DLG2 and VGLL4. Interestingly, three of these genes, FOXP1, SF3B1 and DLG2, have previously been implicated in neurodevelopmental disorders. 相似文献
83.
Gjerdrum C Vallée AM St Clair CC Bertram DF Ryder JL Blackburn GS 《Proceedings of the National Academy of Sciences of the United States of America》2003,100(16):9377-9382
Anomalously warm sea-surface temperatures (SSTs) are associated with interannual and decadal variability as well as with long-term climate changes indicative of global warming. Such oscillations could precipitate changes in a variety of oceanic processes to affect marine species worldwide. As global temperatures continue to rise, it will be critically important to be able to predict the effects of such changes on species' abundance, distribution, and ecological relationships so as to identify vulnerable populations. Off the coast of British Columbia, warm SSTs have persisted through the last two decades. Based on 16 years of reproductive data collected between 1975 and 2002, we show that the extreme variation in reproductive performance exhibited by tufted puffins (Fratercula cirrhata) was related to changes in SST both within and among seasons. Especially warm SSTs corresponded with drastically decreased growth rates and fledging success of puffin nestlings. Puffins may partially compensate for within-season changes associated with SST by adjusting their breeding phenology, yet our data also suggest that they are highly vulnerable to the effects of climate change at this site and may serve as a valuable indicator of biological change in the North Pacific. Further and prolonged increases in ocean temperature could make Triangle Island, which contains the largest tufted puffin colony in Canada, unsuitable as a breeding site for this species. 相似文献
84.
Hiroko P. Indo Hsiu-Chuan Yen Ikuo Nakanishi Ken-ichiro Matsumoto Masato Tamura Yumiko Nagano Hirofumi Matsui Oleg Gusev Richard Cornette Takashi Okuda Yukiko Minamiyama Hiroshi Ichikawa Shigeaki Suenaga Misato Oki Tsuyoshi Sato Toshihiko Ozawa Daret K. St. Clair Hideyuki J. Majima 《Journal of Clinical Biochemistry and Nutrition》2015,56(1):1-7
Fridovich identified CuZnSOD in 1969 and manganese superoxide dismutase (MnSOD) in 1973, and proposed ”the Superoxide Theory,” which postulates that superoxide (O2•−) is the origin of most reactive oxygen species (ROS) and that it undergoes a chain reaction in a cell, playing a central role in the ROS producing system. Increased oxidative stress on an organism causes damage to cells, the smallest constituent unit of an organism, which can lead to the onset of a variety of chronic diseases, such as Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis and other neurological diseases caused by abnormalities in biological defenses or increased intracellular reactive oxygen levels. Oxidative stress also plays a role in aging. Antioxidant systems, including non-enzyme low-molecular-weight antioxidants (such as, vitamins A, C and E, polyphenols, glutathione, and coenzyme Q10) and antioxidant enzymes, fight against oxidants in cells. Superoxide is considered to be a major factor in oxidant toxicity, and mitochondrial MnSOD enzymes constitute an essential defense against superoxide. Mitochondria are the major source of superoxide. The reaction of superoxide generated from mitochondria with nitric oxide is faster than SOD catalyzed reaction, and produces peroxynitrite. Thus, based on research conducted after Fridovich’s seminal studies, we now propose a modified superoxide theory; i.e., superoxide is the origin of reactive oxygen and nitrogen species (RONS) and, as such, causes various redox related diseases and aging. 相似文献
85.
Eva Y.F. Pang Shirley S.M. Fong Mimi M.Y. Tse Eric W.C. Tam Shamay SM Ng Billy C.L. So 《Journal of Physical Therapy Science》2015,27(6):1839-1845
[Purpose] This study investigated the intra-rater, inter-rater and test-retest
reliability of the sideways step test (SST), its correlation with other indicators of
stroke-specific impairment, and the cut-off count best discriminating subjects with stroke
from their healthy counterparts. [Subjects and Methods] Forty-three subjects with chronic
stroke and 41 healthy subjects older than 50 years participated in this study. The SST was
administered along with the Fugl-Meyer motor assessment for the lower extremities
(FMA-LE), the five-times sit to stand (5TSTS) test, the Berg Balance Scale (BBS), the
movement velocity (MVL) by the limits of stability (LOS) test, the ten-metre walk (10mW)
test, the timed “Up and Go” (TUG) test and the Activities-specific Balance Confidence
(ABC) scale. [Results] The SST showed good to excellent intra-rater, inter-rater and
test-retest reliability. The SST counts correlated with 5TSTS times, 10mW times, TUG
times, and the FMA-LE and BBS scores. SST counts of 11 for the paretic leg and 14 for the
non-paretic leg were found to distinguish the healthy adults from subjects with stroke.
[Conclusion] The sideways step test is a reliable clinical test, which correlates with the
functional strength, gait speed, and functional balance of people with chronic stroke.Key words: Balance, Stroke, Rehabilitation 相似文献
86.
Association of androgen‐deprivation therapy with excess cardiac‐specific mortality in men with prostate cancer 下载免费PDF全文
David R. Ziehr Ming‐Hui Chen Danjie Zhang Michelle H. Braccioforte Brian J. Moran Brandon A. Mahal Andrew S. Hyatt Shehzad S. Basaria Clair J. Beard Joshua A. Beckman Toni K. Choueiri Anthony V. D'Amico Karen E. Hoffman Jim C. Hu Neil E. Martin Christopher J. Sweeney Quoc‐Dien Trinh Paul L. Nguyen 《BJU international》2015,116(3):358-365
87.
Assessment of aldehyde dehydrogenase in viable cells 总被引:3,自引:4,他引:3
Jones RJ; Barber JP; Vala MS; Collector MI; Kaufmann SH; Ludeman SM; Colvin OM; Hilton J 《Blood》1995,85(10):2742-2746
Cytosolic aldehyde dehydrogenase (ALDH), an enzyme responsible for oxidizing intracellular aldehydes, has an important role in ethanol, vitamin A, and cyclophosphamide metabolism. High expression of this enzyme in primitive stem cells from multiple tissues, including bone marrow and intestine, appears to be an important mechanism by which these cells are resistant to cyclophosphamide. However, although hematopoietic stem cells (HSC) express high levels of cytosolic ALDH, isolating viable HSC by their ALDH expression has not been possible because ALDH is an intracellular protein. We found that a fluorescent aldehyde, dansyl aminoacetaldehyde (DAAA), could be used in flow cytometry experiments to isolate viable mouse and human cells based on their ALDH content. The level of dansyl fluorescence exhibited by cells after incubation with DAAA paralleled cytosolic ALDH levels determined by Western blotting and the sensitivity of the cells to cyclophosphamide. Moreover, DAAA appeared to be a more sensitive means of assessing cytosolic ALDH levels than Western blotting. Bone marrow progenitors treated with DAAA proliferated normally. Furthermore, marrow cells expressing high levels of dansyl fluorescence after incubation with DAAA were enriched for hematopoietic progenitors. The ability to isolate viable cells that express high levels of cytosolic ALDH could be an important component of methodology for identifying and purifying HSC and for studying cyclophosphamide-resistant tumor cell populations. 相似文献
88.
Corticosteroids have the ability to suppress the production of growth factors and cytokines and are thus implicated in the negative regulation of hematopoiesis. We have shown that the corticosteroids, prednisolone and dexamethasone, were able to effectively protect progenitor cells in four strains of mice against cell-cycle-specific antimetabolic chemotherapy agents. The highest levels of protection against 5-fluorouracil (FU; 200 mg/kg) were achieved when two or three intraperitoneal injections of dexamethasone were administered between - 7 and +3 hours at a dose of 7.5 mg/kg/injection (optimal dose) or by continuous infusion between -4 and +20 hours. This protective effect is manifested as an increase in the number of high proliferative potential colony-forming cells that survive in the bone marrow 3 days after treatment with FU from between 0.5% and 11% to between 10% and 34% of normal. The bone marrow progenitors and blood cell numbers return to normal from 3 to 5 days and 1 to 2 days earlier, respectively. Less dexamethasone than prednisolone is required to give an equivalent protective effect, which is consistent with their anti-inflammatory potency. These findings are further evidence of the negative regulatory role played by corticosteroids, and indicate that the treatment schedules of corticosteroids during cancer therapy need to be reexamined to obtain the maximum benefit from their use. 相似文献
89.
90.