全文获取类型
收费全文 | 4795篇 |
免费 | 183篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 70篇 |
妇产科学 | 47篇 |
基础医学 | 683篇 |
口腔科学 | 88篇 |
临床医学 | 238篇 |
内科学 | 1341篇 |
皮肤病学 | 37篇 |
神经病学 | 401篇 |
特种医学 | 152篇 |
外科学 | 758篇 |
综合类 | 18篇 |
预防医学 | 110篇 |
眼科学 | 78篇 |
药学 | 270篇 |
中国医学 | 25篇 |
肿瘤学 | 653篇 |
出版年
2023年 | 23篇 |
2022年 | 37篇 |
2021年 | 72篇 |
2020年 | 44篇 |
2019年 | 79篇 |
2018年 | 101篇 |
2017年 | 95篇 |
2016年 | 86篇 |
2015年 | 99篇 |
2014年 | 139篇 |
2013年 | 166篇 |
2012年 | 270篇 |
2011年 | 286篇 |
2010年 | 164篇 |
2009年 | 123篇 |
2008年 | 263篇 |
2007年 | 326篇 |
2006年 | 262篇 |
2005年 | 286篇 |
2004年 | 298篇 |
2003年 | 259篇 |
2002年 | 241篇 |
2001年 | 73篇 |
2000年 | 67篇 |
1999年 | 94篇 |
1998年 | 68篇 |
1997年 | 51篇 |
1996年 | 47篇 |
1995年 | 41篇 |
1994年 | 53篇 |
1993年 | 48篇 |
1992年 | 72篇 |
1991年 | 79篇 |
1990年 | 57篇 |
1989年 | 55篇 |
1988年 | 56篇 |
1987年 | 40篇 |
1986年 | 31篇 |
1985年 | 42篇 |
1984年 | 32篇 |
1983年 | 27篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1980年 | 21篇 |
1979年 | 28篇 |
1978年 | 37篇 |
1977年 | 18篇 |
1975年 | 14篇 |
1974年 | 14篇 |
1972年 | 13篇 |
排序方式: 共有5010条查询结果,搜索用时 546 毫秒
41.
Norio Kunieda Akira Suzuki Masayoshi Kinoshita Minoru Imoto 《Macromolecular chemistry and physics.》1972,152(1):35-42
Kinetic studies on the acid-catalyzed reaction of formaldehyde with diphenyl sulfide (DPS) were carried out in acetic acid in the presence of sulfuric acid. The rate of the initial stage of the reaction was found to be in agreement with the following equation. The relative rates of diphenyl sulfide and its homologous compounds in the reaction with formaldehyde gave a good correlation with BROWN -OKAMOTO 's σ⊕ values and a large ρ value. The polar effects of substituents of the substituted diphenyl sulfides on the rates were found to be considerably large. From these results a plausible mechanism of the reaction has been deduced. 相似文献
42.
Akiyoshi Nishikawa Takuji Tanaka Nobuyuki Kanai Kazuo Kato Hideki Mori Masayoshi Takahashi 《Pathology international》1987,37(7):1003-1007
Exfoliative cytopathology of alveolar rhabdomyosarcoma is presented. A 34-year-old male was found to have alveolar rhabdomyosarcoma of the retroperitoneum at autopsy. Ascites was recognized in the course of this disease. Cytological features in the ascites were characterized by relatively small-sized ovoid cells observed singly or in loose clusters. The neoplastic cells possessed small amount of rather vesicular cytoplasm and an eccentric nucleus. The nucleus characteristically revealed multiple deep indentations in the nuclear membrane, a few prominent eosinophilic nucleoli and finely granular or evenly distributed chromatin pattern. These cytological findings, especially the nuclear features, might be useful to differentiate alveolar rhabdomyosarcoma from other neoplasms which consist of relatively small-sized ovoid cells even if the striated muscle origin cannot be confirmed by immunoperoxidase staining. 相似文献
43.
44.
Minoru Imoto Masayoshi Kinoshita Masahiko Nishigaki 《Macromolecular chemistry and physics.》1966,94(1):238-247
The radical mutual copolymerization of p-substituted styrenes, such as p-methoxy-, p-chloro-, p-bromo-, p-cyanostyrene, and styrene was carried out with one another at 30°C. in the dark. As initiator, azobisisobutyronitrile was used. The plots of the copolymerization rates against HAMMETT 's σ values showed no linear relationships and the concave curves were obtained therefrom. The relative reactivities of p-substituted styrenes with a definite p-substituted polystyryl radical, which were shown by the reciprocal of monomer reactivity ratio r1, were plotted against σ values and concave curves were also obtained. The relative reactivities of p-substituted polystyryl radicals with p-substituted styrene were calculated from the ratios r2 and the propagation rate constants in homopolymerization. the plots of them against σ values gave straight lines with different ρ values, according to the polarity of substituents. These results suggest that polar structures in transition state affected markedly the copolymerization rates. The effect of substituents on resonance stabilization was also quantitatively estimated. 相似文献
45.
Honda T Ota H Arai K Hayama M Fujimoto K Yamazaki Y Haniuda M 《Virchows Archiv : an international journal of pathology》2002,441(1):47-52
The etiology of usual interstitial pneumonia (UIP), a progressive lung disease, remains unclear. We examined alveolar structure in UIP three-dimensionally. Lung biopsy specimens from five patients with idiopathic pulmonary fibrosis were used. Sections 150-microm thick were stained with elastica solution for elastic fibers, with alpha-smooth muscle actin antibody for myofibroblasts, with anti-Thomsen-Friedenreich antibody for type-II pneumocytes and with anti-CD34 antibody for blood vessels. We examined them three-dimensionally using a laser confocal microscope or light microscope. In the fibrotic lesions, the thick elastic fibers forming the alveolar framework were not particularly dense considering the reduction in alveolar volume. Near the fibrotic lesions, some of the thin elastic fibers in the alveolar wall were slightly sinuous and ended with rounded tips. Type-II pneumocytes had proliferated and were distributed uniformly over the alveolar surface. Smooth muscle actin filaments were detected only around the alveolar orifice. These findings show that in UIP destruction of the elastic fiber framework of the alveoli may lead to irreversible focal alveolar collapse after damage to the alveolar epithelial cells, and proliferation of type-II pneumocytes may be involved with this elastolysis. 相似文献
46.
Naomi Kawano Takaaki Ito Hitoshi Kitamura Tokuhiko Shibagaki Yoichi Kameda Nobuo Nakamura Masayoshi Kanisawa 《Pathology international》1996,46(6):393-398
The α subunit of a GTP-blndlng protein, Go, was investigated in pulmonary neuroendocrine neoplasms and fetal tissues of the lung by an immunohistochemlcal method. Positive immunostaining for the α subunit of Go (Goα) was found predominantly on the cell membrane and found occasionally in the cytoplasm. Typical carcinoids were all positively stained (9/9), and small cell carcinoma showed weaker and less frequent staining (5 positive cases in 10). Atypical carcinoids were variously stained (3/4). The tendency for obvious neuroendocrine differentiation to be immunohistochemically determined in typical carcinoids and not in small cell carcinoma is also true of staining for neuron specific enolase (NSE), chromogranin A (CG-A) and synaptophysin. In the lung, Goα-immunostaining was positive not only in nerve tissues but also in the airway epithelium. In the fetal lung, serial sections immunostained for NSE, CG-A and Goα confirmed that Goα-immunoreactive cells belong to the neuroendocrine cell population. The biological significance of Goα is unclear in normal and neoplastic lung tissues, but Goα is a useful marker of neuroendocrine cells and neoplasms of the lung. 相似文献
47.
Tamauchi H Terashima M Ito M Maruyama H Ikewaki N Inoue M Gao X Hozumi K Habu S 《International immunology》2004,16(1):179-187
48.
Adult rats emit 22 kHz ultrasonic vocalizations (USVs) in response to aversive stimuli, and these sounds are suggested to have communicative information among conspecifics. It is conceivable that social environment during development of rats has relevance to the emission of 22 kHz USVs. To examine the effects of social environment after weaning on production of stress-induced USVs, we compared the amount of emission of USVs among three groups of rats reared under different conditions after weaning. One group of rats was housed individually, and the other two groups were housed in pairs, in which social hierarchy of the pair was determined by social dominance-subordination relationships. The USVs were induced by acute mild somatic stimuli on the back and neck. Individually reared rats emitted much fewer USVs than pair-reared rats. In addition, socially subordinate rats emitted more USVs compared with socially dominant ones. These results suggest that not only social interaction but also the status in social hierarchy may play an important role in the process of the development of USVs induced by somatic stimuli. 相似文献
49.
Katsuaki Ukai Kazuo Terashima Yutaka Imai Haruhide Shinzawa Yoshimi Okuyama Tsuneo Takahashi Makoto Ishikawa 《Pathology international》1990,40(9):623-634
In an effort to settle the conflicting views on the proliferation kinetics of Kupffer cells (Kc), we performed 2/3 partial hepatectomy on rats injected with Pelikan ink. Using an anti-rat macrophage monoclonal antibody, ED 2, we evaluated the numerical changes in total, carbon-positive ED 2+ cells and carbon-negative ED 2+ cells in the portal and central area. We also analyzed the ultrastructure and peroxidase cytochemistry of various types of cells observed during regeneration. The total numbers of ED 2+ cells in the remaining liver increased rapidly from day 2 to 5, and the number of dividing ED 2+ cells reached a maximum on day 2. Thus, the numerical increase in ED 2+ cells corresponded to the division phase. In contrast, the carbon-labeling experiment showed a continuous increase of carbon negative ED 2+ cells from day 2 to 7. In the central area where division was less frequent, the proportion of carbon-positive cells decreased markedly to 50% on day 7, as against 97% in control rats. These findings suggest the possibility of an influx of carbon-negative Kc in addition to cell division. Ultrastructurally, the presence of carbon-negative "small Kc" and "immature Kc" with morphological features different from those of carbon-positive Kc was demonstrated. Such carbon-negative Kc with a high nucleus-to-cytoplasm ratio and rather few phagosomes, were not observed in control rats. Furthermore, we demonstrated two types of possible precursor cell, i.e. "transitional" forms between monocytes and Kc, and "immature macrophages". The former showed peroxidase activity in some lysosomes as well as in the rough endoplasmic reticulum and nuclear envelope. Our result indicated that the proliferation kinetics of Kc depend upon both local proliferation and influx. 相似文献
50.
Takaaki Ito Hitoshi Kitamura Yoshiaki Inayama Masayoshi Kanisawa 《Pathology international》1988,38(9):1097-1104
Chronic effects of 4-nitroquinoline 1-oxide (4 NQO) on the lungs of Syrian golden hamsters were studied. 4 NQO was subcutaneously injected weekly for 3 weeks at a dose of 20 mg/kg body weight. The animals were sacrificed at the 65th and 80th experimental weeks. Two cases of pulmonary adenomas were demonstrated in the 10 4 NQO-treated animals at the 80th week, and the tumor cells contained cytoplasmic lamellar inclusion bodies. In a previous study, we reported 4 NQO- induced pulmonary endocrine cell hyperplasias in the 4 NQO-treated hamster after the 20th experimental week (Jpn. J. Cancer Res., 77,1986). In the present study, 12 pulmonary endocrine cell hyperplasias were recognized in serial sections of the 24 treated animals. The hyperplastic lesions showed positive immunoreactivity to calcitonin. The hyperplastic lesion did not develop to pulmonary endocrine cell neoplasm. ACTA PATHOL JPN 38 : 1097∼1104, 1988. 相似文献