全文获取类型
收费全文 | 3098篇 |
免费 | 195篇 |
国内免费 | 7篇 |
出版年
2022年 | 6篇 |
2021年 | 37篇 |
2020年 | 19篇 |
2019年 | 23篇 |
2018年 | 38篇 |
2017年 | 26篇 |
2016年 | 55篇 |
2015年 | 102篇 |
2014年 | 107篇 |
2013年 | 188篇 |
2012年 | 180篇 |
2011年 | 166篇 |
2010年 | 102篇 |
2009年 | 99篇 |
2008年 | 178篇 |
2007年 | 208篇 |
2006年 | 175篇 |
2005年 | 190篇 |
2004年 | 197篇 |
2003年 | 158篇 |
2002年 | 176篇 |
2001年 | 76篇 |
2000年 | 90篇 |
1999年 | 70篇 |
1998年 | 47篇 |
1997年 | 42篇 |
1996年 | 28篇 |
1995年 | 29篇 |
1994年 | 23篇 |
1993年 | 23篇 |
1992年 | 47篇 |
1991年 | 37篇 |
1990年 | 40篇 |
1989年 | 31篇 |
1988年 | 28篇 |
1987年 | 31篇 |
1986年 | 32篇 |
1985年 | 26篇 |
1984年 | 20篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1981年 | 21篇 |
1980年 | 14篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 18篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1972年 | 6篇 |
排序方式: 共有3300条查询结果,搜索用时 125 毫秒
71.
72.
Takeshi Shimamoto Nobutake Yamamichi Shinya Kodashima Yu Takahashi Mitsuhiro Fujishiro Masashi Oka Toru Mitsushima Kazuhiko Koike 《PloS one》2013,8(6)
Probably due to caffeine-induced gastric acid secretion, negative effects of coffee upon various upper-gastrointestinal diseases have been precariously accepted, despite the inadequate epidemiological evidence. Our aim is to evaluate the effect of coffee consumption on four major acid-related diseases: gastric ulcer (GU), duodenal ulcer (DU), reflux esophagitis (RE), and non-erosive reflux disease (NERD) based on the large-scale multivariate analysis. Of the 9,517 healthy adults, GU, DU, and RE were diagnosed by endoscopy, and NERD was diagnosed by the symptoms of heartburn and regurgitation without esophageal erosion. Associations between coffee consumption and the four disorders were evaluated, together with age, gender, body mass index (BMI), Helicobacter pylori (HP) infection status, pepsinogen I/II ratio, smoking, and alcohol. We further performed meta-analysis using the random effects model to redefine the relationship between coffee intake and peptic ulcer disease. The eligible 8,013 study subjects comprised of 5,451 coffee drinkers and 2,562 non-coffee drinkers. By univariate analysis, age, BMI, pepsinogen I/II ratio, smoking, and alcohol showed significant associations with coffee consumption. By multiple logistic regression analysis, positively correlated factors with significance were HP infection, current smoking, BMI, and pepsinogen I/II ratio for GU; HP infection, pepsinogen I/II ratio, and current smoking for DU; HP non-infection, male, BMI, pepsinogen I/II ratio, smoking, age, and alcohol for RE; younger age, smoking, and female for NERD. The meta-analyses could detect any association of coffee consumption with neither GU nor DU. In conclusion, there are no significant relationship between coffee consumption and the four major acid-related upper gastrointestinal disorders. 相似文献
73.
Ryosuke Tateishi Shuichiro Shiina Masaaki Akahane Jiro Sato Yuji Kondo Ryota Masuzaki Hayato Nakagawa Yoshinari Asaoka Tadashi Goto Kuni Otomo Masao Omata Haruhiko Yoshida Kazuhiko Koike 《PloS one》2013,8(4)
Background
In the treatment of hepatocellular carcinoma (HCC), hepatic resection has the advantage over radiofrequency ablation (RFA) in terms of systematic removal of a hepatic segment.Methods
We enrolled 303 consecutive patients of a single naïve HCC that had been treated by RFA at The University of Tokyo Hospital from 1999 to 2004. Recurrence was categorized as either intra- or extra-subsegmental as according to the Couinaud''s segment of the original nodule. To assess the relationship between the subsegments of the original and recurrent nodules, we calculated the kappa coefficient. We assessed the risk factors for intra- and extra-subsegmental recurrence independently using univariate and multivariate Cox proportional hazard regression. We also assessed the impact of the mode of recurrence on the survival outcome.Results
During the follow-up period, 201 patients in our cohort showed tumor recurrence distributed in a total of 340 subsegments. Recurrence was categorized as exclusively intra-subsegmental, exclusively extra-subsegmental, and simultaneously intra- and extra-subsegmental in 40 (20%), 110 (55%), and 51 (25%) patients, respectively. The kappa coefficient was measured at 0.135 (95% CI, 0.079–0.190; P<0.001). Multivariate analysis revealed that of the tumor size, AFP value and platelet count were all risk factors for both intra- and extra-subsegmental recurrence. Of the patients in whom recurrent HCC was found to be exclusively intra-subsegmental, extra-subsegmental, and simultaneously intra- and extra-subsegmental, 37 (92.5%), 99 (90.8%) and 42 (82.3%), respectively, were treated using RFA. The survival outcomes after recurrence were similar between patients with an exclusively intra- or extra-subsegmental recurrence.Conclusions
The effectiveness of systematic subsegmentectomy may be limited in the patients with both HCC and chronic liver disease who frequently undergo multi-focal tumor recurrence. 相似文献74.
Keita Nishiyama Akira Kawanabe Hirofumi Miyauchi Fumiaki Abe Daigo Tsubokawa Kazuhiko Ishihara 《Bioscience, biotechnology, and biochemistry》2013,77(8):1444-1451
The aim of this study was to assess the adhesion of Bifidobacterium strains to acidic carbohydrate moieties of porcine colonic mucin. Mucins were extracted and purified via gel filtration chromatography followed by density-gradient ultracentrifugation. The presence of sulfated and sialylated carbohydrates in mucins was shown by enzyme-linked immunosorbent assays using PGM34 and HMC31 monoclonal antibodies (mAbs), respectively. Adhesion of Bifidobacterium strains to mucin preparations was markedly affected by the degree of purification. In eight of 22 strains, we observed increased adhesion to mucin preparations purified by ultracentrifugation. Moreover, in some of these eight strains, adhesion to mucin was reduced by pretreatment with sulfatase and/or sialidase, and competitively inhibited by pretreatment with PGM34 and/or HCM31 mAbs. Our results showed that some Bifidobacterium strains adhered to sulfo- and/or sialomucin and were able to recognize carbohydrate structures of the mAbs epitopes. 相似文献
75.
Shuichi Kaminogawa Shun-ichi Dosako Kunio Yamauchi Kazuhiko Kinoshita 《Bioscience, biotechnology, and biochemistry》2013,77(2):533-539
Conjugates of αs1-,κ-caseins and αs1-,κ-casein complex were prepared with dimethylaminonaphthalenesulfonate and pyrenebutyrate. Their fluorescence lifetimes and the rotational relaxation times were measured by single photon counting technique and fluorescence depolarization technique, respectively. Both dimethylaminonaphthalenesulfonate and pyrenebutyrate conjugates had more than two lifetimes and the longer lifetime of pyrenebutyrate conjugates was near 140 nsec.The rotational relaxation time of pyrenebutyrate αs1-,κ-casein complex was smaller than that of pyrenebutyrate κ-casein polymer, which suggested that the complex formation of αs1- and κ-casein polymers led to dissociation of the κ-casein polymer.Changes of the rotational relaxation time as a function of weight ratio of αs1- and κ-casein polymers (αs1/κ) showed the specific variation and it was suggested that 4 moles of αs1-κ-casein complex were formed from one mole of κ-casein polymer. 相似文献
76.
Kenji Seiwa Yoshiko Miwa Shigetoshi Akasaka Hiroshi Kanno Mizuki Tomita Tomoyuki Saitoh Naoto Ueno Megumi Kimura Yoichi Hasegawa Miki Konno Kazuhiko Masaka 《Ecological Research》2013,28(1):29-41
To evaluate the extent to which landslides affect community dynamics and consequent species diversity in a beech-dominated forest, differences in the composition and size structure of tree species were compared between landslide and adjacent stable (control) stands. Demography and changes in size were compared between the two stands over a 5-year period about 60 years after a landslide. In the control stand, replacement occurred even amongst late-successional species, with beech (Fagus crenata)—the most dominant species—increasing in relative abundance. In the landslide stand, very few large individuals of late-successional species occurred, whereas large individuals of early-successional species occurred only in the landslide stand. The traits indicate that the landslide strongly facilitated species diversity, not only by reducing the dominance of late-successional species, but also by promoting recruitment of early-successional species. However, new recruitment of early-successional species was inhibited in the landslide stand, although we observed succeeding regeneration and subsequent population growth of late-successional species there. As a result, the relative dominance of late-successional species increased with succession after the landslide, thus decreasing future species diversity. In beech-dominant forest landscapes in Japan that include communities with different developmental stages, the mosaic of serial stages may facilitate species diversity after a landslide. 相似文献
77.
Masakazu Atobe Kenji Naganuma Masashi Kawanishi Akifumi Morimoto Ken-ichi Kasahara Shigeki Ohashi Hiroko Suzuki Takahiko Hayashi Shiro Miyoshi 《Bioorganic & medicinal chemistry letters》2013,23(22):6064-6067
We describe a medicinal chemistry approach to generate a series of 2-(1H-pyrazol-1-yl)thiazole compounds that act as selective EP1 receptor antagonists. The obtained results suggest that compound 12 provides the best EP1 receptor antagonist activity and demonstrates good oral pharmacokinetics. 相似文献
78.
Koji Ochiai Satoshi Takita Akihiko Kojima Tomohiko Eiraku Kazuhiko Iwase Tetsuya Kishi Akira Ohinata Yuichi Yageta Tokutaro Yasue David R. Adams Yasushi Kohno 《Bioorganic & medicinal chemistry letters》2013,23(1):375-381
(?)-6-(7-Methoxy-2-(trifluoromethyl)pyrazolo[1,5-a]pyridin-4-yl)-5-methyl-4,5-dihydropyridazin-3(2H)-one (KCA-1490) exhibits moderate dual PDE3/4-inhibitory activity and promises as a combined bronchodilatory/anti-inflammatory agent. N-alkylation of the pyridazinone ring markedly enhances potency against PDE4 but suppresses PDE3 inhibition. Addition of a 6-aryl-4,5-dihydropyridazin-3(2H)-one extension to the N-alkyl group facilitates both enhancement of PDE4-inhibitory activity and restoration of potent PDE3 inhibition. Both dihydropyridazinone rings, in the core and extension, can be replaced by achiral 4,4-dimethylpyrazolone subunits and the core pyrazolopyridine by isosteric bicyclic heteroaromatics. In combination, these modifications afford potent dual PDE3/4 inhibitors that suppress histamine-induced bronchoconstriction in vivo and exhibit promising anti-inflammatory activity via intratracheal administration. 相似文献
79.
Akihiko Kojima Satoshi Takita Tatsunobu Sumiya Koji Ochiai Kazuhiko Iwase Tetsuya Kishi Akira Ohinata Yuichi Yageta Tokutaro Yasue Yasushi Kohno 《Bioorganic & medicinal chemistry letters》2013,23(19):5311-5316
We previously identified KCA-1490 [(?)-6-(7-methoxy-2-trifluoromethyl-pyrazolo[1,5-a]pyridin-4-yl)-5-methyl-4,5-dihydro-3-(2H)-pyridazinone], a dual PDE3/4 inhibitor. In the present study, we found highly potent selective PDE4 inhibitors derived from the structure of KCA-1490. Among them, N-(3,5-dichloropyridin-4-yl)-7-methoxy-2-(trifluoromethyl)pyrazolo[1,5-a]pyridine-4-carboxamide (2a) had good anti-inflammatory effects in an animal model. 相似文献
80.