全文获取类型
收费全文 | 15614篇 |
免费 | 780篇 |
国内免费 | 99篇 |
专业分类
耳鼻咽喉 | 112篇 |
儿科学 | 297篇 |
妇产科学 | 170篇 |
基础医学 | 1968篇 |
口腔科学 | 318篇 |
临床医学 | 1101篇 |
内科学 | 3960篇 |
皮肤病学 | 204篇 |
神经病学 | 998篇 |
特种医学 | 657篇 |
外科学 | 3176篇 |
综合类 | 50篇 |
预防医学 | 408篇 |
眼科学 | 253篇 |
药学 | 1236篇 |
中国医学 | 53篇 |
肿瘤学 | 1532篇 |
出版年
2023年 | 92篇 |
2022年 | 194篇 |
2021年 | 367篇 |
2020年 | 188篇 |
2019年 | 257篇 |
2018年 | 345篇 |
2017年 | 251篇 |
2016年 | 291篇 |
2015年 | 326篇 |
2014年 | 453篇 |
2013年 | 487篇 |
2012年 | 791篇 |
2011年 | 878篇 |
2010年 | 471篇 |
2009年 | 373篇 |
2008年 | 707篇 |
2007年 | 717篇 |
2006年 | 732篇 |
2005年 | 747篇 |
2004年 | 684篇 |
2003年 | 670篇 |
2002年 | 702篇 |
2001年 | 363篇 |
2000年 | 429篇 |
1999年 | 423篇 |
1998年 | 185篇 |
1997年 | 139篇 |
1996年 | 151篇 |
1995年 | 130篇 |
1994年 | 139篇 |
1993年 | 119篇 |
1992年 | 358篇 |
1991年 | 337篇 |
1990年 | 296篇 |
1989年 | 339篇 |
1988年 | 295篇 |
1987年 | 270篇 |
1986年 | 256篇 |
1985年 | 247篇 |
1984年 | 158篇 |
1983年 | 130篇 |
1982年 | 62篇 |
1979年 | 125篇 |
1978年 | 94篇 |
1977年 | 59篇 |
1975年 | 69篇 |
1974年 | 61篇 |
1973年 | 57篇 |
1972年 | 51篇 |
1969年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
A surface graft polymer with one or two phosphorylcholine (PC) polarheads at the terminus of the growing chain end was prepared by sequential reactions on a glass substrate. The dithiocarbamate group covalently bound to glass surfaces was derivatized with one or two PC groups and then irradiated with ultraviolet light in the presence of N,N-dimethylacrylamide (DMAAm). X-ray photoelectron spectroscopy, wettability measurements and dye staining experiment for the PC group showed that the resultant graft copolymers were produced via iniferter-based quasi-living radical polymerization, in which the polyDMAAm graft chain contains one or two PC groups at the terminal end of the graft chain. These polymer surface grafts may help provide biocompatibility. 相似文献
122.
IgE antibody responses induced by transplantation of the nematode Nippostrongylus brasiliensis in rats: a possible role of nematode excretory-secretory product in IgE production. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In order to examine the effective site of sensitization for IgE responses, we transplanted 2000 adult-stage worms of the nematode Nippostrongylus brasiliensis into the duodenum or the peritoneal cavity of naive rats. Total serum IgE began to increase 1 week after the nematode inoculations and reached a peak at week 2. Living worms inoculated into the duodenum induced the highest serum IgE, this being 800 times the level in control animals. Intraperitoneal inoculations of living and dead worms resulted in increases of the serum IgE levels to 120 and 13 times the control level, respectively. The intraduodenal inoculation of living adult worms also induced a significant increase in specific IgE against the excretory-secretory (ES) product of adult N. brasiliensis 1 week later than the rise in total IgE, whereas intraperitoneal inoculations did not induce such an increase. These results suggest that sensitization through the intestinal mucosa with adult N. brasiliensis might be important for the effective induction of both specific and non-specific IgE responses. Since these findings also indicated that factors secreted by living worms play an important role in the induction of total IgE response, the ES product was injected to naive rats for 6 consecutive days (total 2.7-4.4 mg). Intraperitoneal injection of the ES product alone induced a 14.7-fold increase in total IgE without any specific IgE response. This indicates that some constituents of the ES product have the potential to trigger a non-specific IgE response. 相似文献
123.
PURPOSE: There have been few reports on correlations between resection volume of benign prostatic hyperplasia, body mass index (BMI) and estrogen. This study was undertaken to evaluate the correlations. METHOD: In this study, we considered 50 patients who had benign prostatic hyperplasia (BPH) and underwent suprapubic prostatectomy (SPP). Men with prostate cancer or prior prostate surgery were excluded. The relationship between prostate resection volume and BMI was examined. Additionally, patients were divided into two groups according to BMI: less than 25, and more than 25. The two groups were evaluated according to stained estrogen receptors. RESULTS: BMI was correlated positively with prostate volume (p < 0.01). However, positive rates of estrogen receptors showed no significant difference between the two groups. CONCLUSIONS: This was a study describing the relationship between BMI and prostate volume. Obesity has been hypothesized to be associated with BPH because of the endocrine changes in men that occur with age, including increased estrogen and decreased testosterone. Our findings suggest that estrogen may play a pathophysiologic role in benign prostatic hyperplasia. Further studies of large populations are needed to validate this assumption. 相似文献
124.
Hiroko Matsuda 《Pflügers Archiv : European journal of physiology》1986,407(5):465-475
An inward current characterized by a slow inactivation, was induced when the extracellular Ca2– concentration was reduced by EGTA. It was suppressed by replacing external Na– with Tris+ or by D-600, increased by epinephrine, and was not affected by TTX. These findings suggest that this current is carried by Na+ ions through the Ca channels. The Na current decreased in amplitude as the concentration of external divalent cations was elevated. Blocking the Na current by divalent cations could be approximated by a bimolecular interaction between divalent cation and channel, with a dissociation constant of 1.2 M for Ca2+ and 60 M for Mg2+. Single channel currents were recorded in the cell-attached configuration. With a pipette solution of pCa=7.5 or pCa>8, the single channel I-V relationship was linear and the slope conductance was 70–75 pS. For 40 mV depolarizations from the resting potential, unitary currents were smaller at pCa=6 than at pCa=7.5. However, single channel events, which were observed after the repolarizing step to the resting potential, were much the same amplitude. The open time histogram was fitted with a single exponential having a time constant of 1.9 ms at around –40 mV (pCa>8, with 5 M Bay K 8644 in the bath solution), which was decreased with increasing the Ca2+ concentration in the pipette solution. Noise power spectra of patch currents at pCa=6 revealed a high-frequency component at around 1500 Hz. These results suggest that Ca binding to the sites with a high affinity for Ca2+ blocks the Na conductance in Ca channels. Reduction of the unitary current at higher concentrations of Ca2+ might be attributed to a rapid block by Ca2+. 相似文献
125.
Relative frequencies of G (VP7) and P (VP4) serotypes determined by polymerase chain reaction assays among Japanese bovine rotaviruses isolated in cell culture. 总被引:3,自引:5,他引:3
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Y Suzuki T Sanekata M Sato K Tajima Y Matsuda O Nakagomi 《Journal of clinical microbiology》1993,31(11):3046-3049
The relative frequencies of both the G (VP7) and P (VP4) serotypes of 40 bovine rotaviruses isolated in cell culture from diarrheic calves in Japan between January 1983 and February 1991 were determined by recently developed polymerase chain reaction assays. Isolates with G serotype 6 and P serotype 5 (UK-like strains) were most frequently found (42.5%) followed by isolates with G6P11 (17.5%), G6P1 (10%), or G10P5 (10%). Isolates with G10P11 (B223-like strains) were least frequently found (7.5%). The presence of various combinations of G and P serotypes suggests frequent reassortment in nature among bovine rotaviruses. 相似文献
126.
Atsuo Ogura Toshihiko Asano Junichiro Matsuda Minako Koura Masaro Nakagawa Hiroshi Kawaguchi Yutaka Yamaguchi 《Virchows Archiv : an international journal of pathology》1990,417(3):223-228
Summary Glomerular lesions in hereditary nephrotic mice (ICGN strain) were investigated by electron microscopy. The glomeruli of unaffected animals, which appeared normal by light microscopy, had developed an ultrastructural change in the glomerular capillary basement membrane (GCBM). There was a partial thickening of the GCBM with bilaminar splitting of the lamina densa and an electron-dense fibrillar material exhibiting cross-striations. In affected animals, light microscopy revealed a marked thickening of GCBM and an increase of mesangial matrix without cellular proliferaton. By electron microscopy, multilaminar splitting of the lamina densa in the thickened GCBMs and fusion of the epithelial foot processes were observed. In some severely affected animals, immune complex deposition was found in GCBM, but little if any was observed in other animals. In the end, the glomeruli were globally sclerosed. Our findings suggest that initial structural abnormalities in GCBM may play an important role in the onset and development of the disease, though subsequent events such as immune complex deposition would modify the disease. 相似文献
127.
128.
Takao Shioya Hiroko Matsuda Akinori Noma 《Pflügers Archiv : European journal of physiology》1993,422(5):427-435
The present patch-clamp study shows that external Mg2+, Ca2+ and Sr2+ decrease the unit amplitude of inward current through the inward-rectifier K+ channel in a concentration-dependent manner. Sr2+ produces a voltage-dependent flickering block as well, and the fractional electrical distance between the external orifice and the Sr2+ binding site () is 0.73. The decrease of unit amplitude is reversible and voltage independent while it does not increase the noise level on the open-channel current. Unit current decreased by Mg2+ or Ca2+ has a longer mean open time, which is inversely proportional to the unit amplitude. External Mg2+ does not decrease the amplitude of unit outward current. A surface potential shift, measured using voltage-dependent Cs+ block (=1.60), failed to explain the current decrease. Therefore, we conclude that (1) the external divalent cations cause an extremely fast channel block, which appears as a decreased amplitude of the unit current on the recording system; (2) the blocking site (fast site) is present near the external orifice of the channel, and it is separate from the blocking site (slow site) to which Cs+ and Sr2+ bind. 相似文献
129.
Haruyo Nakajima PhDa Satoshi Hachimuraa Shinya Nishiwakia Toshiyuki Katsuki MD PhDb Naoki Shimojo MD PhDb Akio Ametani PhDa Yoichi Kohno MD PhDb Shuichi Kaminogawa PhDa 《The Journal of allergy and clinical immunology》1996,97(6):1342-1349
To study cow’s milk allergy at the cellular level, we assessed the reactivity of peripheral blood mononuclear cells from patients allergic to cow’s milk to αs1-casein, which is one of the major allergens in cow’s milk. Proliferation of the cells to αs1-casein activation showed a rather weak response. Therefore to understand T-cell reactivity to αs1-casein in more detail, we prepared αs1-casein–specific T-cell lines from patients allergic to cow’s milk and established 26 T-cell lines. These T-cell lines could be classified into three groups by analyzing their surface marker expression: those containing predominantly CD4+CD8- T cells, those containing both CD4+CD8- and CD4-CD8+ T cells, and those containing predominantly CD4-CD8+ T cells. The CD8+ T cells were obtained at an unexpectedly higher frequency from the patients. These T-cell lines produced interferon-γ and IL-4. These results suggest that CD8+ T cells specific for αs1-casein and CD4+ T cells were primed by the stimulation with αs1-casein in patients allergic to milk and that both T cells may play a key role in the onset, progression of, or recovery from cow’s milk allergy. (J ALLERGY CLIN IMMUNOL 1996;97:1342-9.) 相似文献
130.
A new algorithmic-based digital filter processing system for real-time continuous blood pressure (BP) measurement and analysis in freely-moving conscious rats has been developed. Real-time recognition of BP waveforms, real-time noise rejection and determination of representative waveform indexes (WIs) at indicated time points using digital filters and Smirnov's rejection test were realized with this system. Digital filters were applied for two different purposes: waveform segmentation and smoothing the calculations of representative WIs. Smirnov's rejection test was used for real-time noise rejection and yielded an accurate rejection rate of 99.99%. The result was that the digital filter processing and Smirnov's rejection test realized accurate real-time BP measurement and analysis in freely-moving conscious rats using a personal computer. 相似文献