全文获取类型
收费全文 | 11047篇 |
免费 | 578篇 |
国内免费 | 84篇 |
专业分类
耳鼻咽喉 | 221篇 |
儿科学 | 160篇 |
妇产科学 | 136篇 |
基础医学 | 1402篇 |
口腔科学 | 391篇 |
临床医学 | 757篇 |
内科学 | 2989篇 |
皮肤病学 | 207篇 |
神经病学 | 737篇 |
特种医学 | 321篇 |
外科学 | 1694篇 |
综合类 | 37篇 |
预防医学 | 341篇 |
眼科学 | 179篇 |
药学 | 713篇 |
中国医学 | 32篇 |
肿瘤学 | 1392篇 |
出版年
2023年 | 71篇 |
2022年 | 140篇 |
2021年 | 239篇 |
2020年 | 114篇 |
2019年 | 157篇 |
2018年 | 197篇 |
2017年 | 167篇 |
2016年 | 199篇 |
2015年 | 196篇 |
2014年 | 244篇 |
2013年 | 318篇 |
2012年 | 577篇 |
2011年 | 572篇 |
2010年 | 292篇 |
2009年 | 285篇 |
2008年 | 470篇 |
2007年 | 533篇 |
2006年 | 530篇 |
2005年 | 577篇 |
2004年 | 493篇 |
2003年 | 498篇 |
2002年 | 485篇 |
2001年 | 370篇 |
2000年 | 407篇 |
1999年 | 366篇 |
1998年 | 145篇 |
1997年 | 108篇 |
1996年 | 115篇 |
1995年 | 75篇 |
1994年 | 78篇 |
1993年 | 71篇 |
1992年 | 279篇 |
1991年 | 212篇 |
1990年 | 206篇 |
1989年 | 196篇 |
1988年 | 198篇 |
1987年 | 185篇 |
1986年 | 190篇 |
1985年 | 158篇 |
1984年 | 115篇 |
1983年 | 95篇 |
1981年 | 42篇 |
1979年 | 82篇 |
1978年 | 58篇 |
1977年 | 43篇 |
1974年 | 62篇 |
1973年 | 43篇 |
1972年 | 49篇 |
1970年 | 45篇 |
1969年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
41.
K Okamoto K Kubota E Kawada H Kurabayashi T Shirakura 《Nihon Ronen Igakkai zasshi. Japanese journal of geriatrics》1991,28(5):693-696
A 70-year-old man was admitted to our hospital because of fever and progressive dyspnea in December 1989. He was already diagnosed as having erythrocytosis secondary to pulmonary fibrosis 4 years previously and the values of his hematocrit (Ht) were maintained between 44.5 and 62.9% by repeated phlebotomy. Immediately after admission, severe diarrhea developed and the Ht value was 61.5%. Around 1:30 a.m. of the 3rd hospital day, he developed disturbance of consciousness. In addition, the serum levels of LDH, CPK, aldolase, and myoglobin of muscle origin increased markedly and the Ht value showed 78.5%. While the level of consciousness was gradually restored by 600 ml phlebotomy and 1,500 ml saline infusion, dysarthria and hemiplegia became evident. The Ht value early in the morning of the 3rd hospital day was reduced to 59.4%. Although cranial CT and MRI performed 74 days and 15 months, respectively, after the onset of the symptoms failed to reveal any abnormal shadow, he was clinically suspected to have cerebral infarction. These findings emphasize that abrupt increase in Ht or blood viscosity is a possible factor triggering cerebral infarction, and adequate control of Ht value is recommended for the prevention of such a condition in the aged. 相似文献
42.
K Sakakibara K Mizuno T Kano M Ohta Y Tomita G Yoshio Y Tokuhashi Y Nishida E Okamoto M Hori 《Gan no rinsho》1986,32(14):1841-1848
The pharmacokinetics and metabolism of carmofur (HCFU) were studied. Sixty-six patients were administered 100 mg of HCFU orally, and the plasma levels of the HCFU fraction (HCFUf) and 5-fluorouracil (5-FUra) were determined at 0, 1, 2, 4 and 6 hours. The average half-life of HCFUf and 5-FUra were 1.05 and 1.31 hours, and the average areas under the curves (AUC) of the plasma concentration were 6.51 hr X mcg/ml and 0.46 hr X mcg/ml, respectively. Surgical specimens of the tumors were obtained about three hours after the administration and assayed for HCFUf. 5-FUra fluorodeoxyuridine-monophosphate (FdUMP), deoxyuridine-monophosphate (dUMP), total thymidylate synthetase (TS total), and non-FdUMP-bound free enzyme (TS free). The TS inhibition rate (IR) was calculated by the follow method: IR = (TS total-TS free)/TS total X 100 levels of the TS total varied from not-detected (less than 0.10 pmol/g) to 20.5 pmol/g. The average FdUMP: dUMP ratio was 3.44 X 10(3), However, more than 80% inhibitions of TS were observed in nine cases (21.4%). The correlation indicates between TS IR and tissue FdUMP level or FdUMP: dUMP ratio were 0.57 and 0.62 in ovarian malignancies respectively. No significant correlations were observed between TS inhibition and levels of tissue 5-FUra or AUC of 5-FUra. 相似文献
43.
Akihiro Ito Tadateru Takahashi Hiromitsu Watanabe Peter Osa Ogundigie Taro Okamoto 《Cancer science》1992,83(10):1052-1056
Mouse liver tumors occurring in C3H/HeN, C57BL/6N and C3B6F1 hybrid (C3H × C57BL) were studied following 252 Cf fission neutron irradiation. Three strains of mice of both sexes (about 30 mice/group) were irradiated once with 252 Cf at doses of 0,12.5, 50 and 200 cGy. The groups were observed for 13 months after irradiation. The incidence of liver tumors in the non-irradiated controls was 0% in both sexes of CS7BL/6N, 11.7% in males and 0% in females of C3B6F1 and 39.5% in males and 11.4% in females of C3H/HeN mice. In the four strains of mice thus far studied, including B6C3F1 hybrid (CS7BL × C3H) which was previously studied, 252 Cf irradiation has increased the tumor incidence dose-dependently in males and in females, but less effectively in females. The mean number and size of liver tumors were clearly correlated with tumor incidence. The incidence was always highest in C3H/HeN mice of both sexes, followed by B6C3F1, C3B6F1 and C57BL/6N mice. The influence of sex hormones was studied in B6C3F1 mice of both sexes after 200 cGy of 252 Cf irradiation. In males, the incidence of liver tumors was significantly decreased from 55.2% to 23.3% and 25.9% after orchidectomy, and in females it was slightly decreased from 27.6% to 14.8% and 18.8% after ovariectomy. Supplementation of testosterone in orchidectomized mice did not restore the occurrence of liver tumors. 相似文献
44.
We compared peroxidizability of neonatal and adult lipoproteins exposed to oxidative stress initiated by an azo-compound. Oxygen uptake showed a two-phase pattern, with slow oxygen uptake in the first phase and faster uptake in the second phase. During the first phase, tocopherol was consumed progressively, inhibiting lipid peroxidation by scavenging peroxy radicals. After the tocopherol concentration fell below a critical level, extensive propagation of chain oxidative reactions produced the rapid oxygen uptake in the second phase. In the first phase of neonatal lipoprotein oxidation, a faster oxygen uptake was observed and the length of this phase was shorter than in adults. The oxygen uptake rate in the second phase was smaller in the neonatal lipoproteins. In other words, neonatal lipoproteins were more susceptible to oxidative stress than were adult ones when tocopherol remained in lipoproteins, but after tocopherol depletion the reverse was true. These results were consistent with the finding that in neonatal lipoproteins the tocopherol/lipid ratio was significantly lower (length of the inhibitory phase was closely correlated to the lipoprotein tocopherol content). In addition, the average number of active bisallylic hydrogen atoms, which are considered to determine the relative susceptibility of polyunsaturated fatty acids to oxidation, was significantly smaller (oxygen uptake rate in the second phase was closely correlated to the active bisallylic hydrogen number) in neonatal lipoproteins, and the ratio of active bisallylic hydrogen to tocopherol content (which closely correlated to oxygen uptake rate in the first phase) was also significantly lower compared with the adult ratio. Under physiologic conditions, an intensive oxidation of lipoproteins sufficient to cause lipoprotein tocopherol to fall below critical levels is unlikely to occur.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
45.
H Okamoto K Yasuura A Matsuura T Akita T Abe A Seki Y Ogawa M Hoshino 《Kyobu geka. The Japanese journal of thoracic surgery》1990,43(7):579-581
A 50-year old man who had acute type A aortic dissection, underwent prosthetic graft replacement of the ascending aorta. Intimal laceration of the ascending aorta was extending into the noncoronary Valsalva sinus just near the aortic annulus, but the competency of the aortic valve was preserved. Reconstruction of the noncoronary sinus was achieved by approximating intimal edge with Teflon felt reinforced buttress suture, then the ascending aorta was replaced by a Dacron prosthetic graft. His postoperative recovery was uneventful. 相似文献
46.
J D Leffert C B Newgard H Okamoto J L Milburn K L Luskey 《Proceedings of the National Academy of Sciences of the United States of America》1989,86(9):3127-3130
Amyloid deposits in the islets of Langerhans of the pancreas are a common finding in non-insulin-dependent diabetes mellitus. The main protein constituent of these deposits is a 37-amino acid peptide known as amylin that resembles calcitonin gene-related peptide, a neuropeptide. We have isolated cDNA clones corresponding to the rat amylin precursor from an islet cDNA library and we show that this peptide is encoded in a 0.9-kilobase mRNA that is translated to yield a 93-amino acid precursor. The amylin peptide is bordered by dibasic residues, suggesting that it is proteolyzed like calcitonin gene-related peptide. The peptide sequences flanking the amylin sequence do not resemble the calcitonin gene-related peptide flanking sequences. RNA hybridization studies show that amylin mRNA is abundant in the islets of Langerhans but is not present in the brain or seven other tissues examined. Dietary changes, such as fasting or fasting and refeeding, have little effect on amylin mRNA expression. This tissue specificity suggests that amylin is involved in specific signaling pathways related to islet function. 相似文献
47.
48.
T Aoki Y Futagami T Konishi S Okamoto T Koyama M Inden M Hamada T Nakano 《Kaku igaku. The Japanese journal of nuclear medicine》1989,26(7):821-828
Clinical significance of reverse redistribution on thallium image was evaluated in 54 patients who had undergone PTCA. Thallium SPECT imaging was performed one week and three to six months after PTCA. Reverse redistribution was detected eight of 54 patients one week after PTCA and five of 38 patients three to six months after PTCA. In the segments with reverse redistribution, reduced regional wall motion and lesser degree of coronary stenosis was common features (p less than 0.05) angiography. In conclusion, reverse redistribution had a tendency to appear in the region with mild myocardial injury and relatively high coronary blood flow after PTCA. But in cases with new occurrence and disappearance of reverse redistribution during follow up period, we can not assess the factors to explain these phenomena. In these segments, "coronary flow reserve", "stunned myocardium", "hibernating myocardium" or other factors may be related. 相似文献
49.
Y Matsushima E Okamoto A Toyosaka E Suzuki K Nose A Nakamura 《Nippon Heikatsukin Gakkai zasshi》1989,25(2):47-54
Daily profile of colonic motor activity was observed in 10 conscious dogs by means of extraluminal force transducers. Each dog was implanted with a set of seven strain, gauges, one on the terminal ileum and the remaining six on the colon equidistantly. The colonic motor activity was basically composed of migrating and non-migrating motor complexes at all six recording sites. Each motor complex was characterized by a tonic contraction superimposed by rhythmic bursts of phasic contractions. During fasted period these motor complexes recurred at a mean interval of 36 min, and a mean duration was 7 to 12 min. Those motor complexes which migrated over at least three recording sites were defined as "migrating", 72% of those observed at the most proximal sites (n = 2680) were migrating, and the remaining 28% were non-migrating. Of those migrating motor complexes 90.4% migrated caudad (iso-peristalsis), while only 9.4% migrated orad (antiperistalsis). During postprandial period the colonic motor complexes at all recording sites uniformly increased their frequency with shorter intervals. Different from the small intestine, the contractile patterns were essentially the same as those of fasted period. The postprandial acceleration of the colonic motor complexes seems to be compatible with gastrocolic response. 相似文献
50.
Role of alphabeta and gammadelta T cells in the host response to Salmonella infection as demonstrated in T-cell-receptor-deficient mice of defined Ity genotypes.
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
B C Weintraub L Eckmann S Okamoto M Hense S M Hedrick J Fierer 《Infection and immunity》1997,65(6):2306-2312
Salmonella spp. are facultative intracellular bacteria which enter the body through the intestinal tract. We studied the roles of T cells expressing either the alpha and beta chains or the gamma and delta chains of the T-cell receptor (alphabeta T cells or gammadelta T cells, respectively) in the host defense against Salmonella using mice genetically deficient in either alphabeta T cells, gammadelta T cells, or both T-cell subsets. These mutant strains of mice were infected orally or intraperitoneally with Salmonella dublin, and the progression of the disease was monitored by determining bacterial numbers in the feces, gut wall, Peyer's patches, mesenteric lymph nodes, spleen, and liver. Since susceptibility to Salmonella infection in mice is strongly affected by the alleles at the Ity locus, T-cell-mutant mice with either the Ity-sensitive or Ity-resistant phenotype were tested for resistance to S. dublin infection. We found that even though large numbers of intraepithelial and mucosal alphabeta and gammadelta T cells populate the normal intestine, they have no role in controlling the invasion of S. dublin into the intestine or the subsequent bacterial replication in the Peyer's patches or gut wall. Furthermore, systemic infections were equally severe for the first 6 days in normal, alphabeta T-cell-deficient, and gammadelta T-cell-deficient mice, and alphabeta but not gammadelta T cells were required for clearance of S. dublin, regardless of the Ity phenotype. However, mice that lacked both T-cell subsets had higher bacterial counts in their livers 15 to 18 days after infection than did alphabeta T-cell-deficient mice, suggesting that gammadelta T cells can contribute to acquired immunity to S. dublin. 相似文献