全文获取类型
收费全文 | 1349篇 |
免费 | 166篇 |
国内免费 | 95篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 35篇 |
2020年 | 32篇 |
2019年 | 32篇 |
2018年 | 39篇 |
2017年 | 42篇 |
2016年 | 35篇 |
2015年 | 58篇 |
2014年 | 70篇 |
2013年 | 81篇 |
2012年 | 134篇 |
2011年 | 135篇 |
2010年 | 67篇 |
2009年 | 42篇 |
2008年 | 59篇 |
2007年 | 71篇 |
2006年 | 62篇 |
2005年 | 63篇 |
2004年 | 44篇 |
2003年 | 56篇 |
2002年 | 56篇 |
2001年 | 34篇 |
2000年 | 43篇 |
1999年 | 23篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1994年 | 8篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 17篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1975年 | 11篇 |
1973年 | 5篇 |
1969年 | 7篇 |
1900年 | 4篇 |
排序方式: 共有1610条查询结果,搜索用时 0 毫秒
101.
Cubukçu A Gönüllü NN Erçin C Alponat A Kaur AC Cantürk Z Paksoy N 《Acta cytologica》2000,44(2):124-127
OBJECTIVE: To investigate the efficacy of imprint cytology in the diagnosis of Helicobacter pylori infection and whether it damages the biopsy specimen for subsequent histologic examination. STUDY DESIGN: Two antral biopsies were taken from 76 patients with dyspeptic symptoms undergoing upper gastrointestinal endoscopy. Imprint cytology was made from the first specimen. This specimen was fixed in 10% formalin and sent for histopathologic examination. The second specimen was directly fixed in 10% formalin for routine histopathologic examination without being used for an imprint. The imprint smears were examined by cytopathologists. The biopsy specimens were examined by pathologists who did not know which specimens were used for the imprints. RESULTS: H pylori was seen in smears from 55 (72%) patients and in both biopsy specimens from the same patients. The pathologists could not recognize the biopsy specimens from which the imprints were made. Concordance between imprint cytology and histopathology was 100%. CONCLUSION: Imprint cytology is a suitable test for H pylori diagnosis, and imprints do not adversely affect the quality of the biopsy specimen. 相似文献
102.
Twenty-eight rhodium, iridium or ruthenium complexes were evaluated for their in vitro antifungal activities against Candida albicans and Candida tropicalis. Fourteen compounds showed an antifungal activity against C. albicans and C. tropicalis with a range of the minimum inhibitor concentrations (MICs) between 16 and 250 micrograms/mL. 相似文献
103.
Gene admixture in the silk road region of China: evidence from mtDNA and melanocortin 1 receptor polymorphism 总被引:19,自引:0,他引:19
Mitochondrial DNA control region segment I sequences and melanocortin 1 receptor (MC1R) gene polymorphism were examined in ethnic populations in the silk road region of China. Both the frequencies of the MC1R variants and the results of mtDNA data in this region presented intermediate values between those of Europe and East and Southeast Asia, which suggested extensive gene admixture in this area and was in general agreement with previous studies. Phylogenetic analysis of the ethnic populations in the Silk Road region that based on mtDNA data didn't show expected cluster pattern according to their ethnogenesis. We suspect that a high migration rate in female among these closely related populations and other three demographic events might account for it. 相似文献
104.
Identification of in vivo substrates of the yeast mitochondrial chaperonins reveals overlapping but non-identical requirement for hsp60 and hsp10. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The mechanism of chaperonin-assisted protein folding has been mostly analyzed in vitro using non-homologous substrate proteins. In order to understand the relative importance of hsp60 and hsp10 in the living cell, homologous substrate proteins need to be identified and analyzed. We have devised a novel screen to test the folding of a large variety of homologous substrates in the mitochondrial matrix in the absence or presence of functional hsp60 or hsp10. The identified substrates have an Mr of 15-90 kDa and fall into three groups: (i) proteins that require both hsp60 and hsp10 for correct folding; (ii) proteins that completely fail to fold after inactivation of hsp60 but are unaffected by the inactivation of hsp10; and (iii) newly imported hsp60 itself, which is more severely affected by inactivation of hsp10 than by inactivation of pre-existing hsp60. The majority of the identified substrates are group I proteins. For these, the lack of hsp60 function has a more pronounced effect than inactivation of hsp10. We suggest that homologous substrate proteins have differential chaperonin requirements, indicating that hsp60 and hsp10 do not always act as a single functional unit in vivo. 相似文献
105.
106.
Energy Storage: Bilayer Structure with Ultrahigh Energy/Power Density Using Hybrid Sol–Gel Dielectric and Charge‐Blocking Monolayer (Adv. Energy Mater. 19/2015)
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
107.
108.
109.
Roger Beeden Jeffrey Maynard Marjetta Puotinen Paul Marshall Jen Dryden Jeremy Goldberg Gareth Williams 《PloS one》2015,10(4)
Full recovery of coral reefs from tropical cyclone (TC) damage can take decades, making cyclones a major driver of habitat condition where they occur regularly. Since 1985, 44 TCs generated gale force winds (≥17 metres/second) within the Great Barrier Reef Marine Park (GBRMP). Of the hurricane strength TCs (≥H1—Saffir Simpson scale; ≥ category 3 Australian scale), TC Yasi (February, 2011) was the largest. In the weeks after TC Yasi crossed the GBRMP, participating researchers, managers and rangers assessed the extent and severity of reef damage via 841 Reef Health and Impact Surveys at 70 reefs. Records were scaled into five damage levels representing increasingly widespread colony-level damage (1, 2, 3) and reef structural damage (4, 5). Average damage severity was significantly affected by direction (north vs south of the cyclone track), reef shelf position (mid-shelf vs outer-shelf) and habitat type. More outer-shelf reefs suffered structural damage than mid-shelf reefs within 150 km of the track. Structural damage spanned a greater latitudinal range for mid-shelf reefs than outer-shelf reefs (400 vs 300 km). Structural damage was patchily distributed at all distances, but more so as distance from the track increased. Damage extended much further from the track than during other recent intense cyclones that had smaller circulation sizes. Just over 15% (3,834 km2) of the total reef area of the GBRMP is estimated to have sustained some level of coral damage, with ~4% (949 km2) sustaining a degree of structural damage. TC Yasi likely caused the greatest loss of coral cover on the GBR in a 24-hour period since 1985. Severely impacted reefs have started to recover; coral cover increased an average of 4% between 2011 and 2013 at re-surveyed reefs. The in situ assessment of impacts described here is the largest in scale ever conducted on the Great Barrier Reef following a reef health disturbance. 相似文献
110.
Jen C. Wang Hemant Sindhu Chi Chen Ajay Kundra Muhammad I. Kafeel Ching Wong Stephen Lichter 《PloS one》2015,10(3)
Myelofibrosis (MF), including primary myelofibrosis, post-essential thrombocythemia MF, and post-polycythemia vera MF, has been reported to be associated with autoimmune phenomena. IMiDs have been reported to be effective in some patients with MF, presumably for their immune-modulator effects. We therefore sought to elucidate the immune derangements in patients with MF. We found no differences in T regulatory cells (Treg) and T helper 17 (Th17) cells in MF patients and normal healthy controls. However, we found significantly elevated soluble interleukin 2 alpha (sIL2Rα) in MF patients compared to those with other myeloproliferative neoplasm diseases and normal healthy controls. Our studies with MF patients further revealed that Treg cells were the predominant cells producing sIL2Rα. sIL2Rα and IL2 complex induced the formation of Treg cells but not the formation of Th1 or Th17 cells. sIL2Rα induced CD8+ T cell proliferation in the presence of Treg cells. Monocytes or neutrophils had no effect on the production of sIL2Rα by Treg cells. Furthermore, we found plasma sIL2Rα levels were correlated to the auto-immune serology in MPN patients and ruxolitinib significantly inhibits the sIL2Rα production by the Treg cells in MF patients which may explain the effects of ruxolitinib on the relief of constitutional symptoms. All these findings suggest that sIL2Rα likely plays a significant role in autoimmune phenomena seen in patients with MF. Further studies of immune derangement may elucidate the mechanism of IMiD, and exploration of immune modulators may prove to be important for treating myelofibrosis. 相似文献