全文获取类型
收费全文 | 6768篇 |
免费 | 137篇 |
国内免费 | 9篇 |
学科分类
工业技术 | 6914篇 |
出版年
2023年 | 27篇 |
2022年 | 43篇 |
2021年 | 103篇 |
2020年 | 47篇 |
2019年 | 57篇 |
2018年 | 102篇 |
2017年 | 71篇 |
2016年 | 113篇 |
2015年 | 69篇 |
2014年 | 130篇 |
2013年 | 246篇 |
2012年 | 186篇 |
2011年 | 258篇 |
2010年 | 195篇 |
2009年 | 190篇 |
2008年 | 224篇 |
2007年 | 221篇 |
2006年 | 206篇 |
2005年 | 180篇 |
2004年 | 177篇 |
2003年 | 189篇 |
2002年 | 167篇 |
2001年 | 162篇 |
2000年 | 165篇 |
1999年 | 196篇 |
1998年 | 649篇 |
1997年 | 410篇 |
1996年 | 273篇 |
1995年 | 217篇 |
1994年 | 205篇 |
1993年 | 186篇 |
1992年 | 106篇 |
1991年 | 94篇 |
1990年 | 97篇 |
1989年 | 97篇 |
1988年 | 84篇 |
1987年 | 78篇 |
1986年 | 73篇 |
1985年 | 79篇 |
1984年 | 58篇 |
1983年 | 55篇 |
1982年 | 59篇 |
1981年 | 58篇 |
1980年 | 39篇 |
1979年 | 46篇 |
1978年 | 31篇 |
1977年 | 49篇 |
1976年 | 75篇 |
1975年 | 16篇 |
1972年 | 12篇 |
排序方式: 共有6914条查询结果,搜索用时 31 毫秒
101.
T Matsuba M Yamada H Suzuki A Kanai O Isozaki T Yoshida T Tsushima K Yasukawa 《Canadian Metallurgical Quarterly》1995,118(2):265-270
Starting with a previously isolated cDNA for human thyrotropin receptor (TSHR), we established a transformed myeloma cell line, SP56, which expresses human TSHR on its cell surface. Binding analysis showed that SP56 bears 1.1 x 10(5) TSHR per cell with a Kd of 2.2 x 10(-10) M. Using the purified cellular membrane, we established a TSH binding inhibition immunoglobulin (TBII) assay for autoantibodies against TSHR. We compared it with the TBII assay utilizing porcine thyroid membranes expressing porcine TSHR, which has been widely used for TBII assay, by using 96 serum samples from patients with autoimmune thyroid disease and normal individuals. Our TBII assay was more sensitive than the one using porcine TSHR: of 38 sera of patients which were judged negative for autoantibodies to TSHR (TBII value below 10%) by the latter assay, 28 were positive (above 20%) in our assay. By using a perfusion culture system, we obtained as many as 3 x 10(10) SP56 cells, from which 3,450 mg protein of the membrane could be purified; this is sufficient for 15,000 assays. The results indicate that the membrane of the myeloma cell line SP56 is more suitable for use in the TBII assay than the porcine thyroid membrane, in terms of sensitivity to autoantibodies against TSHR in human sera. 相似文献
102.
103.
Experimental demonstration of soliton data transmission over unlimited distances with soliton control in time and frequency domains 总被引:1,自引:0,他引:1
Nkazawa M. Suzuki K. Yamada E. Kubota H. Kimura Y. Takaya M. 《Electronics letters》1993,29(9):729-730
A 2/sup 9/-1 pseudorandom-binary-sequence soliton signal has been transmitted experimentally over one million km for the first time with no degradation in the bit error rates. The synchronous modulator was driven by a timing clock signal extracted from the transmitting data signal. These results mean that it is possible to send soliton data signals over unlimited distances through the use of soliton control in the time and frequency domains.<> 相似文献
104.
105.
Surface characteristics of the bovine oocyte and its investments before, during, and after maturation, and fertilization in vitro were evaluated by scanning electron microscopy (SEM). Oocyte diameters were also measured during SEM analysis of the oocyte. The cumulus cells manifested a compact structure with minimal intercellular spaces among them in the immature oocytes. These became fully expanded with increased intercellular spaces after maturation in vitro, but contracted again after fertilization. The zona pellucida (ZP) showed a fibrous, open mesh-like structure in the maturing and matured oocytes. The size and number of meshes on the ZP decreased dramatically after fertilization. The vitelline surface of immature oocytes was characterized by distribution of tongue-shaped protrusions (TSPs) varying in density. After 10 and 22 hr of maturation incubation, oocyte surface microvilli (MV) increased to become the predominant surface structure, and TSPs decreased substantially. The vitelline surface of fertilized oocytes (at 6 and 20 hr) was similar to that of the matured oocytes, but unfertilized oocytes had less dense MV than did fertilized oocytes (at 20 hr). The diameter of the oocytes decreased from 99 to 80 microns during maturation and increased to 106 microns after insemination (P < 0.05). Membrane maturation was characterized by surface changes from a TSP-predominant pattern to a MV-predominant pattern. Thus, the bovine oocyte maturation process was found to involve the expansion of cumulus cells and the maturation of the ZP, which changes dramatically upon fertilization. Also, volumetric changes occurred in ooplasm processed for SEM following oocyte maturation and insemination. 相似文献
106.
T Igarashi S Suzuki M Takahashi T Tamaoki T Shimada 《Canadian Metallurgical Quarterly》1998,9(18):2691-2698
Gene transfer into specific tissues or cell types is a key technique in the development of gene therapy. Modification of vector particles such that they selectively bind to the target cells has been attempted, but the limitation of this approach is the low transduction efficiency. Here, we show that a two-step gene transfer system can be used for efficient cell targeting. With this strategy, and using a high-titer adenoviral vector containing a tissue-specific promoter, we have engineered a system in which only target cells become susceptible to retrovirus-mediated transduction. In a model experiment, we constructed an adenoviral vector (Ad.AFPEcoRec) containing the ecotropic retrovirus receptor (EcoRec) gene under the control of the alpha-fetoprotein (AFP) promoter. A binding assay showed that after transduction with AD.AFPEcoRec, EcoRec molecules were efficiently expressed in AFP+HepG2 cells, but not in AFP-HeLa and AFP-HLE cells. The EcoRec-expressing HepG2 cells could be stably transduced with ecotropic retroviral vectors, whereas HeLa and HLE cells remained highly resistant to retrovirus-mediated gene transfer. The apparent titer on HepG2 cells was greater than 2 x 10(5) CFU/ml. Because various tissue-specific promoter/enhancer elements are available, the two-step system could be used as a general strategy for both ex vivo and in vivo targeted gene transfer. 相似文献
107.
Rei Endo Kei Matsumoto Hiroshi Shigeno 《Journal of Network and Systems Management》2012,20(3):353-371
Massively Multiplayer Online (MMO) games have large-scale virtual environments. Here, we propose a load distribution technique called the Group Based Load-distribution Technique with Virtual Group (GBLT-VG) that utilizes Peer-to-Peer (P2P) communication to maintain scalability under high user density conditions in MMO virtual environments. A common problem of P2P virtual environments is that user group behavior frequently generates high user density conditions. Existing techniques to manage the virtual environment cannot maintain performance in such high user density situations. The proposed technique, GBLT-VG, reduces area management loads of manager peers by introducing a new manager who manages a user neighbor group. GBLT-VG forms the user neighbor group efficiently by using party function under high user density conditions caused by users?? cooperative behaviors. In addition, GBLT-VG reduce the management load by using a virtual group when a number of parties is small, thereby decreasing the existing managers?? loads dynamically. This paper also presents simulation results demonstrating how GBLT-VG can reduce the average number of users managed by the server. 相似文献
108.
Yuya Hattori Michiyo Suzuki Zu Soh Yasuhiko Kobayashi Toshio Tsuji 《Artificial Life and Robotics》2012,17(2):173-179
The pharyngeal pumping motion to send food to the bowel is a rhythmic movement in Caenorhabditis elegans. This paper proposes a simulation-based approach to investigate the mechanisms of rhythm phenomena in the pharyngeal pumping motion. To conduct the simulations, first, we developed a pharyngeal muscle model including 29 cell models which simulate the activity of each cell as a membrane potential based on FitzHugh-Nagumo equations. Then, to compare the response of the model with that of C. elegans, we calculated the electropharyngeogram (EPG), which represents the electrophysiological responses of the pharyngeal cells, using the simulated membrane potentials. The results confirmed that our model could generate the EPG similar to that measured from C. elegans. We proposed a computer simulation of the pumping motion to investigate the mechanisms of rhythm phenomena in living organisms. 相似文献
109.
Takeyuki Suzuki Tsutomu Yamazaki Hiroshi Yoshioka Kuniyuki Hikichi 《Journal of Materials Science》1988,23(1):145-149
Amorphous SnOx films were deposited by ion-beam sputtering on sintered alumina substrates. Amorphous film sensors were prepared by annealing the films at 300° C for 2 h in air. The thickness dependence of resistivity and hydrogen gas sensitivity were measured at 150° C over the thickness range 1 to 700 nm. A resistivity maximum was observed in ultrathin films. Resistivity increased by three orders of magnitude with increasing film thickness from 0.9 to 7.4 nm and then decreased by five orders of magnitude from 7.4 to 35 nm. Ultrathin film sensors showed sensitivity maxima around a thickness of 10 nm. Sensitivity and resistivity of ultrathin films were significantly influenced by the thermal expansion coefficient and the surface state of the substrate. 相似文献
110.
The preparation and characterization of indium oxide (InO
x
)/tin oxide (SnO
y
) multilayered films deposited by ion-beam sputtering are described and compared with indium tin oxide (ITO) films. The structure and the optoelectrical properties of the films are studied in relation to the layered structures and the post-deposition annealing. Low-angle X-ray diffraction analysis showed that most films retained the regular layered structures even after annealing at 500° C for 16 h. As an example, we obtained a resistivity of 6×10–4 cm and a transparency of about 85% in the visible range at a thickness of 110 nm in a multilayered film of InO
x
(2.0 nm)/SnO
y
(0.2 nm)×50 pairs when annealed at 300° C for 0.5 h in air. Hall coefficient measurements showed that this film had a mobility of 17 cm2 V–1 sec–1 and a carrier concentration (electron density) of 5×1020 cm–3. 相似文献